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Once more, why should going be reading this--an expert, or somebody who needs some introduction setting? Really do hard work on your figures--numerous readers would invest more time seeing your figures while going through the content. 4) Mention your story by cover, stating the figures. A paper could be like a narrative, yet not at all like historical writing wherein you are not asked to state what was done sequentially, and not at all like the stories of investigation or detective stories wherein you can leave the principle point at the very last stage. If in case you have selected the figures well, you are presently something like eighty percent of the route there. Try not to stress about the length as of right now. 5) Now work on the introduction and essays survival the paragraph on conclusion. The introduction has to cover letter mirror the larger picture and spot your work in setting, while referring to on technology and fitness in younger proper references. Within a short paper, you do not have to refer to everything remotely identified with your work, yet you would prefer not to cover forget significant contributors. Try not to cite yourself unless it is truly pertinent.
The introduction is the place you will achieve or lose the group of gathering or audience, including analysts. Generally towards the end of the research paper on religion, introduction is a section which begins In this paper, we. That is the place you should have the capacity to show the highlights of the paper in only a couple of sentences. Truly work at your introduction. It is directly behind the cafe cover letter, abstract and the figures as far as making an impact on the reader. Concerning conclusions, what you do here relies upon the journal. A few journals simply don't write the closing sections. Others conclude with the discussion, make a summary of the outcomes/results again quickly, and after that provide viewpoints on conceivable future work. 6) Finally write the abstract. The abstract should be clear, brief, offer the setting, and outline the essay on technology and fitness in younger generation, fundamental purposes of the research paper.
As irritating as it is in cover, some way or another that there is an algorithm for this, there truly is, and it lives up to the expectations. The general format and the manner in which it makes you consider what every sentence is essays, doing could be extremely useful, notwithstanding when creating abstracts for journals of non-Nature. 7) Now do the editing and proofreading. Re-read and again read the document, revamping things so as to make them more clear and compact. Set it aside for a day or more and after that make a reading of it with freshness. Ensure the coauthors do the editing and proofreading too. The methodology is without a doubt to move some content onto the page and afterward edit it, instead of struggle regard attempting to cafe cover letter compose something flawless from the beginning. You are considering making a physics thesis document? Give us a chance to study furnish you with a few tips on how you can make your life easier with regard composing a physics thesis. Let's begin with deciding the topic. A thesis requires having a great topic.
In any case, how would we pick a good topic for research? There are a few things which you need to cover apply while selecting a topic. Clinical Support Case? These elements are likewise useful to cafe cover all kinds of cause essay addiction theses. In the first place, the topic selected need to be important. It ought to have sense and could convey incredible advantages to the readers. A good thesis could be composed on cafe letter, a good topic. Thus students need to effect computer figure out how to choose an cafe letter, impressive topic for the thesis. Such topics must be intriguing for the readers. In the event that the writer does not have any interest on the topic, then the writer also will not be able to once to the draft an impressive thesis paper on letter, the topic. Secondly, you need to have the capacity to apply relevant methods of research to bring the impressive results.
This relates to essay in younger feasibility. Cover? Third, you must be intrigued with the topic. This would spare the energy and time of the student which is research paper on religion, spent on doing the research and studying another topic. Besides, the topic must be narrow and specific so that the student could finish the thesis within the provided deadline period and the word count and as far as possible. As far as you are motivated to compose the paper, then you could make a high standard work with best results. Ultimately, there ought to be sufficient motivated materials of research for cafe cover, you. Since it is a topic of high technicality, you ought to paper on religion and science have adequate data of information on the topic chosen to letter set up any of computer addiction your claims made within in the thesis.
What are the important parts of a physics thesis document? You can make use of the cafe, same type of structure which you know already. Indeed, a wide range of thesis documents, regardless of eb white lake what the topic might be, will all incorporate the same parts and cover letter pages as in any thesis. You require an abstract which is additionally known as the executive summary, the introductory paragraph which exhibits the background of the topic, the essay in younger generation, review of literature which incorporates other sources of research, methodology which clarifies the discussions and cafe cover letter results, data and assessment, methods of research, and obviously the conclusion which would wind up each one of the results or outcomes with regard to essay more to the lake the research. Is it important to perform experiments?
We all realize that physics would dependably include tests and exercises to cafe cover letter demonstrate a characteristic conduct of nature. Be that as it may, you could in any case compose a thesis document without performing experiments. It is dependent upon you what research methods you might want to make use of. In the page on methodology, clarify whether you are going to utilize data mining or interviewing, surveying, experiments or any other method to deliver results with regard to research. Now let us give you few tips with regard to making a research report. You can outline the best experiment in the world, however if are not able to draft an clinical decision study, impressive report then no one would consider the cover, results of your study as important. The principal thing you need to do is verify that you have performed and designed a great experiment.
When it is done and you have heaps of clinical decision support system results/outcomes, you could exhibit them to the world. Most of the science reports ought to cover have the same structure: 1) Title 2) Introduction 3) Method 4) Results 5) Discussion 6) Conclusion 7) References. 1) Title: The title should not be too long but should depict precisely what the experiment is cause essay, all about. Case in cafe cover letter, point, Mold Growth lets us know nothing though The Effect Of Temperature On Mold Growth tells everyone as to what the essay on technology in younger, experiment is in fact all about. 2) Introduction: In this area, it is essential to offer the reasons as to why you selected this type of experiment and demonstrate the background study you had done for it. You need to cafe cover make the assumption that someone reading your test may not know anything regarding the eb white once more, topic, so you need to provide them a fast summarization. Cover Letter? You could tell them something regarding 'The History of on technology and fitness Pendulums'. Cafe Letter? There is one issue; how would you keep the introduction in brief, whilst attempting to make someone know regarding your topic? This is what i did on spring, wherein you need to utilize references, at times known as citations. For each bit of data included, you ought to tell the reader where it originated from. Cafe Cover Letter? Whether from essay on technology generation magazines, books, the web or your professor, in the event that you incorporate your references, some person inspired by cafe letter, your topic could without much of a difficulty read them and what i did break essay get to know more on the topic.
At last, you ought to incorporate the statement pertaining to the hypothesis. This is in fact what you are attempting to demonstrate or discredit. Cafe? Case in point 'Mold develops speedier at increased temperatures' or 'Costly brands of the paper towel ingest more water than less expensive ones' are hypotheses which can be tested. 3) Method: Here you must state precisely the methods and equipment you utilized. What you need to recall is that someone may need to test your outcomes/results so you must ensure that they find themselves able to perform precisely the same test with precisely the same type of equipment. It is a smart idea to research paper incorporate a list of the various equipments you utilized and orderly guidelines on what you had done. 4) Results: Here you depict what you have found. Cafe Letter? In this segment, you ought not to talk about what your outcomes or results intend; just what you found.
You need to paper on religion attempt to be correct and provide numbers rather than just various observations. Use diagrams and tables as they are simpler for individuals to comprehend effectively. Be mindful so as not to put in cover, several types of charts only for the purpose of break essay doing it. Each table and chart ought to be clear and cafe cover alluded to in the effect computer, content. 5) Discussion: The discussion part is the section wherein you do interpretation of your outcomes and attempt to clarify what they intend. This is cafe cover, called importance. You ought to call attention to research paper on religion whether your hypothesis is demonstrated or proved, negated or uncertain, on the off chance that you are not certain in one method or the other. In case if your hypothesis is cafe, demonstrated or proved, awesome, yet the universe of science does not stay constant. Here you ought to cause effect guess as to where science would go next or what tests you can do next. Case in point, on cafe letter, account of the test of mold bread, in the wake of experimenting the impact of temperature, you could check if the measure of light has an on technology in younger generation, impact on the scale of growth. On the off chance that your theory wasn't right or doubtful, this is not an issue.
There is no good and bad in science, just answers. Regardless of the cover letter, possibility that your hypothesis wasn't right, the universe of science has still studied something. In the discussion you need to depict as to on technology and fitness in younger why the cover, experiment did not lead to the outcomes you anticipated. Perhaps your introductory hypothesis wasn't right; however perhaps there were a few imperfections in your experimental method or design. Research Paper? You ought to state as to cafe letter why it may not be right or what alterations you could make if you somehow happened to do the experiment once more. Speak the truth.
No one is going to rebuff you for having these issues, just for not comprehending why. Indeed, even incredible scientists such as Charles Darwin as well as Stephen Hawking have had defects in their theories so you are following some great people's example if your experimenting did not function precisely as to how you arranged! 6) Concluding paragraph: It is always a smart thought to research paper and science compose a short summarization of the conclusion towards the end of the report so as to make things to cafe cover letter be clear to what break essay the reader. Let us give you a specimen of a physics report : See the detailed description underneath: Experimental Investigation with regard to C/D: 1) Introduction: How is the circumference relating to a circle identified with regard to cafe the diameter across? In this laboratory, you outline an experiment so as to test a hypothesis regarding the geometry of the circles.
This movement is a prologue to lab examinations. It is intended to offer practical experience on taking estimations, assessing data, and drawing deductions without needing any extraordinary information on the subject. 2) Equipment (with regard to each group): Vernier calipers, Metric ruler, At minimum five items with widths. 10 cm: (marble, penny, PVC chambers, D cell). Process: Design a process of experiment to test the accompanying hypothesis. 'The circumference (C) with regard to a circle is in direct proportion to eb white essay more its diameter (D)'.
Ensure that you record whatever you do as you tend to do it, so that the process area pertaining to your report precisely and cafe totally shows what had done. 3) Assessment: Do have an understanding that as the semester advances, you would be relied upon to take increased responsibility regarding choosing how to assess the data. Drawing upon legitimate inferences from the data is an essay on technology in younger, indispensable aptitude for scientists and engineers. The directions for assessing the data for cover, a majority of the laboratories won't be as nitty gritty as the guidelines beneath. 4) Numerical Analysis: Calculate the proportion C/D for every object. Gauge the accuracy of on spring every estimation of C/D. 5) Assessment of Graphs: Use of Excel to letter build a chart of C versus D. Essays? Utilization of Excel to cafe show the and science, equation regarding the most suitable fit line by cafe cover, means of your data. On Spring Break? Utilize the cafe cover letter, LINEST capacity to assess the vulnerability in the slant and intercept regarding the most suitable fit line. Ensure you make interpretations of the significance regarding the intercept and the slope.
6) Questions which need to be considered: How do your graphs and calculations show support or invalidate the hypothesis? Does your analysis of generation graphs concur with your estimations? Do your outcomes for the C/D proportion concur with acknowledged theory? Even with all these tips, it is really very hard to do physics research and writing . If you require writing editing and cafe letter proofreading assistance, just get in touch with us today. Effect Essay Addiction? Our pricing is quite competitive, and you can see the prices on our pricing page. You can place your orders through our order form page. You can also contact us through our enquiry page. These 'Price List' (blue button for 'pricing page'), 'Click Here To Order Now' (red button for cover, 'order page') and 'Click Here To Make An Enquiry' (blue button for 'contact us' page) are given on the left hand side of this web page, towards the end of the page. DISCLAIMER: Our company offers custom papers to global clientele such as term papers, essays, dissertation, thesis, reports other writing services inclusive of eb white essay once more to the lake research material, and they are to be used for reference assistance purposes or studying purposes only or are meant to serve as examples for your own work.
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Writing Resumes and Cover Letters. In Canada, employers expect to receive a resume and cover letter that identifies the position you are applying for and summarizes your relevant experience. The goal is to highlight your education, skills and experience, and demonstrate the value you will bring to the position. Your resume and cover letter are your first introduction to a prospective employer, and cafe should be written clearly and professionally. Before you start writing, think about: Your qualifications and skills: what would you contribute to support, the company or organization? Why would you be a valuable employee? Your background: what education, experience or accomplishments do you want to cover letter, highlight? Your expertise: do you have specific skills that would be useful in this job? Your personality: what personal skills is the support case study employer looking for cafe letter that you have?
Time management? Multi-tasking? Project management? The position itself: what skills are required for this job? What experience do you have that is similar? The company or organization: what do you know about the research paper and science company’s mission, strategic goals, or industry? Developing a resume and cover letter requires time and cafe cover letter effort. While you may want to survival, have a “master” copy on cafe, hand, it is important to on technology and fitness generation, customize your resume and cover letter each time you apply for a job. This shows prospective employers that you are interested in the specific position they are offering, and it allows you to focus your resume and cover letter to show exactly how you fit the cafe letter requirements of the job. Chronological versus functional Information to clinical support system, include What not to include LinkedIn.
There are two basic types of resume: chronological and cafe cover letter functional. Most Canadian resumes are chronological , and it is what most employers expect. Eb White Essay Once. They are easy to scan and provide a clear timeline of your work and cafe letter experience. This style is useful for most professions, and is probably the type of resume you will want to cause effect, develop. Chronological resumes list your work experience by date, starting with the most recent at the top. They can also help demonstrate how you’ve developed in your career, or taken on new responsibilities over cover, time. Chronological resumes look like this . Functional resumes are less common, but can be useful if you have little work experience or you’re switching careers, because they emphasize your skills rather than your work history. In a functional resume, you group your work experience by essays on wilderness skill, rather than position. It is cover letter, important, however, to still indicate where you learned each particular skill, so that employers understand how you are qualified. Eb White Essay More. If you write a functional resume, you should also still include a brief list of cover letter, positions held, along with the dates you held them.
A sample functional resume looks like this . Combination resumes are another option, using both chronological and functional aspects, but this is on technology in younger generation, usually only for high-level executives with a vast amount of cover, experience. Combination resumes can look like this . For more information on these formats, and to decide which is support study, best for you, read this Monster.com article, “Should you use a chronological or functional resume?” There are several standard categories of information that employers will look for in your resume. These are: Contact information Education Work history and experience Technical skills Other information like relevant awards, association membership, or volunteer experience. It is important to letter, include your full contact information so employers can get in touch with you. Place your contact information at the top of the cause addiction page, and cover write your name in larger font so that it stands out from the rest of the page.
Many people put their contact information in the document header, as it looks professional and leaves more room on the page for other information. Include your name, mailing address, phone number, and email address. If you have a professional blog or twitter account, you can provide a link to that as well, but only if these are current, professional, and related to essays survival, the job you are applying for. List the cafe degrees and diplomas you’ve obtained, starting with the most recent. Provide the name of the school, the city where it’s located, your area of study, and the dates of your program or graduation. You can also list additional training here, such as accreditations, licences, or certifications. Effect Computer Addiction. In Canada, most people do not include high school graduation information if they have completed post-secondary education. If you are a new graduate, you may want to include a brief list of cover letter, relevant courses you’ve completed, or any scholarships awarded. Include the effect essay computer following information for each relevant job you’ve held: Job title Name of the company or organization where you worked Dates of employment (including just the years is usually sufficient, unless you worked there for a short amount of time)
For each position, also provide a summary of your job responsibilities, functions, and accomplishments. Be as specific as you can, and quantify your experiences whenever possible; for example, if you were a supervisor, list exactly how many people you supervised. This helps the employer understand the scope of cafe cover letter, your experience. Include any promotions you received by listing new job titles or additional responsibilities you took on. Remember to use action words to describe what you’ve achieved. Do you have any specialized skills that are relevant to the position you are applying for? If so, include them.
These could include qualifications like specific computer or software skills, or special drivers’ licenses. Include any additional information that you think is relevant to research paper, the job and helps you stand out from cafe cover other candidates. This could include additional language skills, professional memberships, publications, or awards. Also include volunteer experience that relates to the position you are applying for. Employers value relevant volunteer experience, and this is a useful way to what i did break, show how you’ve gained experience even if you don’t have much work history. Additional tips for cover what to include are found in Career Cruising’s Employment Guide. In Canada, you do not include personal information in your resume such as: Age, place or date of what i did break, birth Marital status Immigration status Social Insurance Number. You are also not expected to provide a photo of yourself, unless you are applying for work as a model or actor. Do not provide references unless the job posting specifically asks you to include them in cafe letter, your application.
If you do need to provide references, list them on essay, a separate page, rather than in your resume. Cover. Most employers will only request references after you’ve had an interview. LinkedIn is a popular social media site where you can post information about your work experience and education. Many employers check job applicants’ LinkedIn profiles, and on religion it is a good way to promote your skills online. Employers may also be interested to cover, see who you are connected to more to the lake, professionally, and which organizations or professional associations you are a member of. Remember that LinkedIn profiles are public, so be sure to keep yours up-to-date and professional.
Creating a basic LinkedIn profile is free. For more information, or to set up a profile, visit the LinkedIn webpage . Do your research Header Body Closing Tips. Your cover letter is letter, your chance to introduce yourself to a prospective employer, and explain why you think you are the best candidate for the job. Cover letters should always be included when you are applying in response to a job advertisement. Your cover letter is also a good place to cause effect computer addiction, include skills that are hard to categorize under any single job position. For example, if good communication skills, organization, or multi-tasking are important qualifications for cover letter the job you are applying for, use your cover letter to explain how you demonstrate these in the workplace. Sample cover letters can be found here. The first step to essays on wilderness, writing a good cover letter is to cafe cover, do your research. Spend some time learning more about the specific job, and system study the company or organization. This is an cafe cover, important step to show employers that you understand the position you are applying for, and that you are interested in and knowledgeable about the company itself.
To learn more about the job, think about the tasks you would be required to carry out. Look at essay in younger generation, similar job postings to cafe letter, find typical duties. You might want to look at the National Occupational Classification website to view lists of typical duties to get a better idea of what the essays on wilderness position might involve. You may also consider arranging an informational interview with the company’s Human Resources department, to learn more about the letter position. Take a look at the Networking for essays on wilderness survival Employment guide for more information on cover letter, how to arrange an informational interview. To learn more about the company, look at their website for eb white once to the lake information. Mission and vision statements are good ways to learn about a company’s values and objectives, while marketing material and cafe annual reports can provide information about in younger generation key executives, recent projects, and new directions. It is cafe, also important to write a new cover letter for research on religion each position you apply for. Your letter should be targeted at the specific job you’re applying for, so that you highlight the most important skills and cafe experience.
The more customized your letter is, the more easily the essay and fitness in younger generation employer can imagine you in their company. Cover letters should include the following information at the top of the document: TIP: if you’ve placed this information in letter, a header on your resume, use the same header for essays your cover letter Employer’s full address. Whenever possible, address your letter to a specific person. If no one is cafe letter, named in the job posting, you can address your letter to the Human Resources Department or Hiring Committee, or Sir/Madam. The body of the cover letter is where you explain why you are interested in the position, what skills you would bring to the position, and what experience you have that makes you a suitable candidate. In the opening paragraph, explain what position you are applying for; include the position or application number if there is one in the advertisement. Explain why you are interested in on wilderness survival, this position and cafe cover company, and include a brief statement of what you would bring the job.
Explain how you learned about this position: did you see an effect essay computer addiction, advertisement? Hear about it from a current employee? Next, summarize your relevant skills and experience that qualify you for cover letter this job. Focus on your strengths, and provide specific examples of survival, work you’ve completed. Don’t just repeat your resume: the cover letter employer will be reviewing that as well. Instead, use your cover letter to what i did break, expand on your resume, and provide details about how your skills will be a valuable addition to the company. Try to cover letter, link your skills with the position’s requirements. Be sure to use keywords from the job posting to what, match your skills to the ones they’re looking for. Lastly, include a summary of your relevant personal, or “soft”, skills, like teamwork, leadership, organization, or communication skills. These are often hard to cafe cover letter, include in your resume, but are important to employers, who are looking for candidates with both the right qualifications and the right personal “fit”. Finish your letter by explaining that you’ve attached your resume, and that you are interested in case, an interview to letter, learn more about the position.
Assume that the employer will have a positive response to your resume, and thank them for their time reviewing your application. Finally, sign off using “Sincerely” followed by your full name. If you are submitting a paper copy of your application, be sure to sign the letter. Most employers do not require a scanned copy of your signature on an electronic application. When writing your cover letter, keep these tips in mind:
Using the same header for your cover letter and resume looks professional and consistent If you are submitting your cover letter in hard copy, print your letter on good-quality 8.5? ? 11? paper Keep a copy of what letters you send for your reference; they’re also a good starting point for your next application. Most employers appreciate a short, concise resume and cause essay computer addiction cover letter, as they will be reviewing many applications. Try to cafe, keep your cover letter to 1 page and your resume to decision system, 2 pages . If you are at a senior or executive level, or if you have a lot of work experience, however, make your application longer to ensure you have shared all the information you need to. When writing your cover letter and resume, be sure to leave lots of “white space” , or areas without text, in the document. This helps to draw your reader to the most important parts of your application, without overwhelming them. You can create more white space by cover using bulleted lists, headings, and tabs. Just be careful to not have too much white space – don’t give the impression that you have nothing else to say. Consistency is what i did on spring, also important.
Use the cafe same font throughout your resume and cover letters, and the same font size (except where you may enlarge or bold your font for emphasis). Essay. If you use round bullets in cover letter, one section, don’t use square bullets elsewhere. Effect Addiction. Paying attention to these small details show you are conscientious in letter, your work. Include the page number and essays on wilderness your name on page 2 of your resume (and any additional pages), so that if the pages of your application are shuffled, the employer can easily gather your information back together. Because your application is cover letter, your introduction to prospective employers, be sure to carefully proofread your resume and essays survival cover letter.
Some people find it helps to print a draft and review it by hand. Don’t forget to cover letter, use Canadian spelling throughout. You can usually set your word processing software to run spell-check in Canadian English. Some examples of Canadian, versus American or British, spelling are available online . Most employers now want to receive applications electronically. If the employer specifies what file format they would like to receive, use that. If they do not specify a format, combining your cover letter and resume into a single PDF file is quite standard, and easily opened by most software programs. Remember to name your file professionally, and to include your name. If the employer requests a hard-copy application, print your cover letter and resume on good quality 8.5? ? 11? paper, and submit them, unfolded, in essay addiction, a large envelope.
Still need more information? Try looking at the following resources: The Vancouver Public Library also has a large collection of resume and cover letter resources, including: VPL collection call number 650.14205 G7381b Best Canadian cover letters. VPL collection call number 650.142 G7381bc1 The perfect resume.
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50 Inspiring Resume Designs: And What You Can Learn From Them. Your resume or CV may be one of the most important projects you ever design. It can make or break job applications, open doors to new careers, make a great (or dismal) first impression. When you send out your resume, you’re really sending out cafe cover a piece of yourself. Essay On Technology In Younger Generation. So make sure it’s representing you to your best advantage. Just like how you dress your best for cafe letter an interview, it’s important to give your resume the same treatment — to make sure it’s polished and presentable. The 50 resume designs below span a wide range of styles, from strictly businesslike to ultra creative — browse through them to clinical support case study, get some ideas for cafe letter updating your own resume. Designing your own is easy with our wide collection of beautiful resume templates. Click the image to see more resume templates. Starting off your resume strong with a bold header, like in eb white once lake this design by Shed Labs for Loft Resumes, draws attention to your name and makes it more memorable. You can also include a few keywords or descriptors under your name that sum up who you are as a candidate.
This chessboard-style layout is certainly striking, giving each category its own distinct space. But Mikha Makhoul’s resume is cover letter still somewhat subdued thanks to the simple black-and-white color scheme; it doesn’t sacrifice professionalism for eb white more to the lake visual interest. Some well-placed shadows can make your resume pop, literally — giving it a 3D appearance and creating the illusion of depth. Cafe Cover Letter. Errol Veloso explains how he chose the colors of his design purposefully: blue to symbolize his creative side and on wilderness red to symbolize his analytic side. Letter. Try using shapes and frames for emphasis.
You can experiment with geometric shapes (circles, squares, rectangles), ribbons, or solid or dashed lines. What On Spring Break Essay. Here, Michael Long frames his name and his role to cafe letter, help them stand out. Essay Once To The. A cohesive color scheme of cool blues and minty hues gives this information-packed, infographic-style resume by Joseph Acena a visual theme and cafe an orderly, coordinated look. Using a horizontal orientation (instead of the clinical support system case study traditional vertical format) immediately gives your resume an edge in cafe letter terms of attracting attention. Essays On Wilderness Survival. Other strong points of this design by Justin Schueler include a balanced, un-crowded layout and plenty of cafe negative space. Eb White To The. There seems to be a trend, at cover letter, least in industries where you can take some risks with your resume, to forget the stuffy business lingo and show that there’s a human behind the piece of paper.
Using a more conversational tone, as David Elgena has done with his “Hello, nice to meet you. Clinical Decision System Case Study. Here’s a little about me” header at the top of this resume, may help you create rapport with the cover person who’s reviewing your application before you even meet them. What I Did Break. This resume by Kyle Robertson features a custom crest with Kyle’s name and cafe letter a catchy tagline. Creating a distinctive personal brand or style for yourself (such as a personal logo, a color scheme, a nice selection of fonts, etc.) gives your work an essay and fitness in younger extra sheen of professionalism (and an opportunity to show off your abilities). Plus, once you put the work in, this “brand” is something you can use over and over again — on cafe cover letter, letterhead, business cards, social media profiles, you name it. For a unique take on traditional resume colors, try light text on a dark background, as Abdullah Al Mamun has done here. Essay. Just make sure that your font is weighty enough to be easily readable and not get lost against the background. This clean resume by Patrick Rogan uses a bright splash of color and whittles down the information to cover, only the basics (skills and essays past positions). Icons in cafe cover letter the skills section provide a visual reference that still complements the simplistic style.
Printing your resume on textured paper can give an impression of quality, craftsmanship, or luxury. If a color other than white seems inappropriate for your industry, try a white or cream-colored paper with a slight texture for an ultra-professional, upscale look. This example by S.N. Clinical Support Case Study. Carter, printed on a recycled or kraft-style paper, gives the resume a custom, hand-printed feel. When applying for cafe letter a position where a more creative approach isn’t appropriate, it’s always a safe bet to opt for research a simple, text-based resume with clean fonts. Here, Frank Schamhart has embellished his resume slightly with minimal use of an accent color and a small personal portrait. If you’re after a job in the arts or some other highly visual industry, make your resume a mini portfolio like illustrator Rianti Hidayat has done here. Bradley Brooks keeps his resume businesslike with a classic black-and-white color scheme, but livens things up with a modular layout and a personal logo. Cafe Letter. Infographic-style resumes have become popular, and they can be effective when done well.
But they should be more than a collection of pretty pictures; the images should, at a glance, tell something about you and complement or enhance the text, like in eb white more to the lake this resume design by Rachel Winter. If you’re seeking work in an industry where appearance is important, or the job has asked you to include a portrait, try integrating it into your resume. Cover. It doesn’t have to be the center of attention, though — you can make it a bit more subtle by on spring essay, using a small picture or placing it behind a colored screen, like in Egotype’s resume template. Letter. Mailing out some resumes? Make opening yours up a memorable experience, like Amber Van Mieghem has done with this clever folding resume. On Religion And Science. Wishing you could infuse a little creativity into your plain, corporate resume? Try a monogram with your initials, like Bill Mawhinney has done for this resume template. It adds a little style while still keeping the overall presentation very businesslike. You can use the same graphic on cover, your cover letter to give your application a polished, pulled-together look. If you have some creative leeway in creating your resume, using a non-rectangular shape will be sure to attract attention, like John Mujica’s round resume does here.
If you do format your resume in any unusual shape, just make sure all the research on religion and science text is readable. Cafe. You’ve only got one name. Make it memorable. If it’s unique, highlight it. Make it big and bold, like Fredrik Andresen did on his resume. Computer Addiction. Give the hiring manager something to zero in on. Your font choices can change the whole character of your resume. For instance, the rounded fonts with soft edges that Louis Omari has used for his resume have a more casual, friendly feel than sharper, serif fonts might have. Need to show your qualifications on the run?
Post your resume online and cover letter make it mobile-friendly, like Julien Renvoye has done. You can include your resume on your personal website or even post it to networking platforms like LinkedIn. Use blocks of color and/or lines to separate different sections of your resume, give it structure, and make it easy to navigate visually. This template from effect essay, Beautiful Resumes features vibrant colors, but you could just as easily get the same effect with a more subtle color scheme. If you’re going the cafe infographic route, think of effective ways that you can use different types of graphs to represent your skills, experience, or background, like Martin Suster did here. Organizing your resume with columns, like this three-column layout Anton Yermolov used, keeps the information tidy, creates clear divisions between sections, and helps you keep everything sharply aligned. Use a sidebar in essay once your resume to call attention to extra (or extra important) information that you want to highlight.
Here, Ola Hamdy used a colored sidebar to separate her personal and contact information from her educational and professional details. Although this resume design is text-heavy, Gershom Charig mixes things up with a two-color scheme and cover letter a word cloud to creatively represent the essay addiction breadth of cafe cover letter his skills and experience. Similar in function to the word cloud above, various sizes of circles represent Silviu Schiau’s proficiency in various areas, such as management and design. The size of the circles corresponds with his amount of experience — a fresh way to illustrate core competencies. Give the person looking at your resume an excuse to find out more about you. Including a link to essays, your website or portfolio (or even a QR code, as Krysten Newby has done here) acts as a good prompt. If your job history includes working for big companies with recognizable logos, feature them on your resume. Letter. Tamas Leb has included space to do so on essay in younger, this resume template, and cafe letter it makes an impressive statement, even at a glance.
For creative resumes, a theme can give you a starting point to research, build a one-of-a-kind design and think about innovative ways to cafe, present your information. Here, Peter Kisteman’s laboratory theme makes a strong visual statement and clinical decision study gives his artistic background a scientific, experimental dimension. Putting your resume in a folder or other kind of holder gives you more space to showcase your experience and accomplishments, plus the cafe letter extra tactile feature makes it memorable, as with this design from S1M. The vertical timeline on the outside offers an immediate visual representation of the essays on wilderness candidate’s career history. Cafe Cover. This traditional black, white, and gray design by cause effect, Brice Seraphin brightens up quite nicely with some turquoise as an accent. This can be done with any color (and you may want to tone it down depending on your industry), but vibrant hues have particular impact. Besides being another nice example of using an accent color, this design by Adam Rozmus keeps things clean and simple, showing that resumes don’t have to be fancy to make a good impression. Letter. If competition is stiff, try standing out with a resume package that gives you some space to demonstrate your abilities, develop a personal brand, and include more information than the limited area of a one-page resume allows for. Here, Sabrae Precure uses a distinct color scheme and custom illustrations to stand out paper and science from the crowd. This resume by Gabriel Valdivia combines a traditional format (the typical positions, dates, and short descriptions) with pictorial elements that provide a more personal touch.
As if to say that a normal paper resume just won’t cut it, Alison Root got clever with her resume presentation, which demonstrates that she thinks outside the box. Cafe Cover. This sample resume from Rahul Chakraborty features bold typography and bright colors for a high-impact look that will make people take notice. On Wilderness Survival. There may be times when it’s ok to let your sense of humor shine through in your resume; it makes you more relatable, more likable. For instance, check out the pronunciation guide Nick Iannuccilli provided for his difficult last name. Using a border is a good way to add a little bit of color to your resume, as Evelien Callens has done here, without worrying about looking unprofessional. Stylistically, this design is a good compromise between customary and more creative resumes. The two-color, mostly traditional layout uses graphic elements sparingly but purposefully. Cafe. As a nice touch, Dan Hernandez has branded his cover letter with the same style, which is a smart idea if your job application involves submitting multiple documents. On Spring. Sometimes you have to do what you can to cafe cover letter, get noticed. For an illustrator like Lucia Paul, hand-drawing her resume is both appropriate for her industry and gives her a standout way to on technology in younger generation, display her skills. Big, bold typography, a high-contrast color scheme, and a well-organized presentation all combine to cafe cover, make sure Joao Andrade’s resume gets looked at.
No long-winded explanations of job roles here. Just the essay once more to the lake essentials — enough to get someone interested in wanting to know more about letter Gianina Santiago and her background. Clean, sans-serif fonts, relatively little text, and lots of white space give Maxat Malbekov’s resume a sleek look that’s easy to achieve if you condense your resume down to only the most relevant information. Once Lake. If you have a lot of information you need to fit on cover letter, one page, take a tip from this design by Halle Rasco and use easy-to-read fonts and research paper on religion and science clear headings for each section. Need to keep your resume fairly conservative?
A two-column layout with a businesslike blue-gray accent color gives this otherwise traditional resume from ResumeBaker some extra interest. Syril Bobadilla’s illustrations are whimsical and kid-friendly, and her resume reflects that style. Notice how she also created matching business cards for a cohesive personal brand. Cafe Cover Letter. Even if your industry doesn’t allow as much creative expression as someone in the arts, you can express your personality in more subtle ways, like through font choices or an i did on spring break accent color. Resumes don’t always have to read from cafe cover, left to right, top to essay on technology generation, bottom.
You can play with the layout of cafe letter your resume to make the best and most visually interesting use of the clinical support study space you have available, like Milena Filipova has done here. You can use a grid structure to cafe cover letter, organize your resume and make it easier to what on spring break, navigate, similarly to how Orlando Silva designed this template. If applicable, you might also try including some pieces from your portfolio right on cover letter, the resume (so your abilities are on display at essay computer, first glance). Cafe Cover Letter. As you can see from the examples above, there are many approaches you can take to clinical system case, designing your resume. But no matter what style or format you choose, there are a few things you want to make sure to get right: Readable text Industry-appropriate style (if unsure, play it safe with a conservative design.) Updated and accurate information No spelling/grammar errors. Now it#8217;s your turn.
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cmu thesis database Java(TM) - see bottom of page. Our valued sponsors who help make this site possible. Note that this page is very large. Cafe Cover. The tips on this page are categorized in other pages.
Use the clinical decision, tips index page to access smaller focused listings of tips. This page lists many other pages available on the web, together with a condensed list of cafe, tuning tips that each page includes. For the most part I've eliminated any tips that are wrong, but one or two may have slipped past me. Remember that the tuning tips listed are not necessarily good coding practice. They are performance optimizations that you probably should not use throughout your code. Essay On Technology. Instead they apply to speeding up critical sections of code where performance has already been identified as a problem. The tips here include only those that are available online for free. I do not intend to summarize any offline resources (such as the various books available including mine, Java Performance Tuning). The tips here are of very variable quality and usefulness, some real gems but some dross and quite a bit of repetition. Comments in square brackets, , have been added by me.
Use this page by using your browser's find or search option to letter, identify particular tips you are interested in on eb white essay once lake the page, and follow up by reading the referenced web page if clarification is necessary. This page is currently 411KB. This page is updated once a month. Cafe Cover. You can receive email notification of any changes by subscribing to the newsletter. Performance planning for managers (Page last updated February 2001, Added 2001-03-21, Author Jack Shirazi, Publisher OnJava). Tips: Include budget for performance management. Create internal performance experts. Set performance requirements in the specifications.
Include a performance focus in the analysis. Require performance predictions from the design. Create a performance test environment. Test a simulation or skeleton system for validation. Integrate performance logging into the application layer boundaries. Performance test the i did on spring essay, system at multiple scales and tune using the resulting information Deploy the cover letter, system with performance logging features. A long list of most of the tuning techniques covered in my Java Performance Tuning book (Page last updated August 2000, Added 2000-10-23, Author Jack Shirazi, Publisher O'Reilly). Tips: [Since the referred to page is already a summary list, I have not extracted it here. Especially since there are nearly 300 techniques listed. Check the research paper and science, page out directly]. Comparing the performance of LinkedLists and ArrayLists (and Vectors) (Page last updated May 2001, Added 2001-06-18, Author Jack Shirazi, Publisher OnJava).
Tips: ArrayList is faster than Vector except when there is cafe, no lock acquisition required in HotSpot JVMs (when they have about the same performance). Vector and ArrayList implementations have excellent performance for essay once lake, indexed access and update of elements, since there is no overhead beyond range checking. Adding elements to, or deleting elements from the end of a Vector or ArrayList also gives excellent performance except when the capacity is exhausted and the internal array has to be expanded. Inserting and deleting elements to cafe letter, Vectors and ArrayLists always require an array copy (two copies when the internal array must be grown first). On Technology And Fitness Generation. The number of elements to be copied is proportional to [size-index], i.e. to the distance between the cafe cover, insertion/deletion index and the last index in the collection. The array copying overhead grows significantly as the eb white essay once more to the, size of the collection increases, because the number of elements that need to be copied with each insertion increases. For insertions to Vectors and cafe letter ArrayLists, inserting to the front of the collection (index 0) gives the worst performance, inserting at the end of the collection (after the effect computer, last element) gives the best performance. LinkedLists have a performance overhead for indexed access and update of cafe letter, elements, since access to any index requires you to traverse multiple nodes. LinkedList insertions/deletion overhead is dependent on the how far away the insertion/deletion index is from the closer end of the collection. Synchronized wrappers (obtained from Collections.synchronizedList(List)) add a level of indirection which can have a high performance cost.
Only List and Map have efficient thread-safe implementations: the Vector and eb white essay once Hashtable classes respectively. List insertion speed is critically dependent on cafe the size of the collection and essay in younger the position where the element is to be inserted. For small collections ArrayList and LinkedList are close in performance, though ArrayList is generally the faster of the cafe cover, two. Essay To The Lake. Precise speed comparisons depend on the JVM and the index where the object is cover, being added. Pre-sizing ArrayLists and on technology in younger generation Vectors improves performance significantly. Cafe Cover Letter. LinkedLists cannot be pre-sized. ArrayLists can generate far fewer objects for the garbage collector to reclaim, compared to and science, LinkedLists.
For medium to large sized Lists, the location where elements are to inserted is critical to the performance of the list. ArrayLists have the cover letter, edge for research, random access. A dedicated List implementation designed to match data, collection types and data manipulation algorithms will always provide the best performance. Cafe Cover Letter. ArrayList internal node traversal from the start to the end of the collection is significantly faster than LinkedList traversal. Consequently queries implemented in essays on wilderness, the class can be faster. Iterator traversal of all elements is cafe cover, faster for ArrayList compared to essay once more lake, Linkedlist.
Using the cover, WeakHashMap class (Page last updated June 2001, Added 2001-07-20, Author Jack Shirazi, Publisher OnJava). Tips: WeakHashMap can be used to reduce memory leaks. Keys that are no longer strongly referenced from the application will automatically make the corresponding value reclaimable. Clinical Decision Support System. To use WeakHashMap as a cache, the keys that evaluate as equal must be recreatable. Using WeakHashMap as a cache gives you less control over when cache elements are removed compared with other cache types. Clearing elements of a WeakHashMap is a two stage process: first the key is reclaimed, then the cafe letter, corresponding value is released from the WeakHashMap. String literals and once more other objects like Class which are held directly by cafe cover letter, the JVM are not useful as keys to a WeakHashMap, as they are not necessarily reclaimable when the application no longer references them.
The WeakHashMap values are not released until the WeakHashMap is altered in some way. For predictable releasing of values, it may be necessary to add a dummy value to the WeakHashMap. If you do not call any mutator methods after populating the WeakHashMap, the what i did break essay, values and internal WeakReference objects will never be dereferenced [no longer true from 1.4, where most methods now allow values to be released]. WeakHashMap wraps an internal HashMap adding an extra level of letter, indirection which can be a significant performance overhead. [no longer true from 1.4]. Every call to essays survival, get() creates a new WeakReference object. [no longer true from cafe cover letter, 1.4]. WeakHashMap.size() iterates through the keys, making it an in younger operation that takes time proportional to the size of the WeakHashMap. [no longer true from cover, 1.4].
WeakHashMap.isEmpty() iterates through the eb white once lake, collection looking for a non-null key, so a WeakHashMap which is empty requires more time for isEmpty() to return than a similar WeakHashMap which is not empty. [no longer true from 1.4, where isEmpty() is now slower than previous versions]. A high level overview of technical performance tuning, covering 5 levels of tuning competence. (Page last updated November 2000, Added 2000-12-20, Author Jack Shirazi, Publisher O'Reilly). Tips: Start tuning by examining the application architecture for potential bottlenecks. Cafe Cover Letter. Architecture bottlenecks are often easy to spot: they are the paper on religion and science, connecting lines on the diagrams; the single threaded components; the components with many connecting lines attached; etc. Ensure that application performance is measureable for the given performance targets. Ensure that there is a test environment which represents the running system. This test-bed should support testing the application at different loads, including a low load and a fully scaled load representing maximum expected usage. Cover. After targeting design and architecture, the biggest bang for your buck in on religion and science, terms of improving performance is choosing a better VM, and cover then choosing a better compiler.
Start code tuning with proof of essays on wilderness, concept bottleneck removal: this consists of using profilers to identify bottlenecks, then making simplified changes which may only improve the performance at the bottleneck for a specialized set of activities, and proceeding to the next bottleneck. After tuning competence is gained, move to full tuning. Cafe. Each multi-user performance test can typically take a full day to what i did break essay, run and analyse. Even simple multi-user performance tuning can take several weeks. After the easily idenitified bottlenecks have been removed, the cafe letter, remaining performance improvements often come mainly from targeting loops, structures and algorithms. Clinical Decision Case. In running systems, performance should be continually monitored to ensure that any performance degradation can be promptly identified and addressed. Chapter 4 of cafe letter, Java Performance Tuning, Object Creation. (Page last updated September 2000, Added 2000-10-23, Author Jack Shirazi, Publisher O'Reilly). Tips: Establish whether you have a memory problem. On Spring. Reduce the number of temporary objects being used, especially in cafe letter, loops. Avoid creating temporary objects within frequently called methods. Clinical Support System Study. Presize collection objects.
Reuse objects where possible. Empty collection objects before reusing them. Cafe. (Do not shrink them unless they are very large.) Use custom conversion methods for research paper on religion and science, converting between data types (especially strings and streams) to reduce the number of cafe cover letter, temporary objects. Define methods that accept reusable objects to be filled in with data, rather than methods that return objects holding that data. Support Case Study. (Or you can return immutable objects.) Canonicalize objects wherever possible. Cafe Cover. Compare canonicalized objects by identity. On Wilderness Survival. [Canonicalizing objects means having only cafe letter, a single reference of an object, with no copies possible]. Create only the number of research paper on religion, objects a class logically needs (if that is a small number of objects). Replace strings and other objects with integer constants. Compare these integers by cover letter, identity. Use primitive data types instead of essay once more, objects as instance variables. Avoid creating an object that is only for accessing a method. Cover Letter. Flatten objects to reduce the number of nested objects. Essays On Wilderness. Preallocate storage for large collections of objects by cafe cover, mapping the essays on wilderness, instance variables into multiple arrays.
Use StringBuffer rather than the string concatenation operator (+). Use methods that alter objects directly without making copies. Create or use specific classes that handle primitive data types rather than wrapping the cover letter, primitive data types. Consider using a ThreadLocal to study, provide threaded access to singletons with state. Use the final modifier on instance-variable definitions to create immutable internally accessible objects. Use WeakReference s to hold elements in large canonical lookup tables. (Use SoftReference s for cache elements.) Reduce object-creation bottlenecks by targeting the letter, object-creation process. Keep constructors simple and inheritance hierarchies shallow. Avoid initializing instance variables more than once. Use the clone() method to avoid calling any constructors. Clone arrays if that makes their creation faster. What On Spring. Create copies of cafe cover letter, simple arrays faster by initializing them; create copies of complex arrays faster by cloning them.
Eliminate object-creation bottlenecks by moving object creation to an alternative time. Create objects early, when there is spare time in the application, and i did break hold those objects until required. Use lazy initialization when there are objects or variables that may never be used, or when you need to cafe, distribute the load of creating objects. Use lazy initialization only when there is a defined merit in the design, or when identifying a bottleneck which is alleviated using lazy initialization. My article on basic optimizations for queries on paper and science collections (Page last updated September 2000, Added 2000-10-23, Author Jack Shirazi, Publisher O'Reilly). Tips: Use short-circuit boolean operators instead of the normal boolean operators. Eliminate any unnecessarily repeated method calls from loops. Eliminate unnecessary casts. Cafe Cover. Avoid synchronization where possible.
Avoid method calls by implementing queries in a subclass, allowing direct field access. Use temporary local variables to manipulate data fields (instance/class variables). Use more precise object typing where possible. Before manual tuning, HotSpot VMs are often faster than JIT VMs. On Religion. But JIT VMs tend to benefit more from manual tuning and can end up faster than HotSpot VMs. Article about optimizing queries on Maps. (Page last updated November 2000, Added 2000-12-20, Author Jack Shirazi, Publisher JavaWorld). Cafe Letter. Tips: Avoid using synchronization in read-only or single-threaded queries.
In the SDK, Enumerators are faster than Iterators due to the specific implementations. Eliminate repeatedly called methods where alternatives are possible. Iterator.hasNext() and Enumerator.hasMoreElements() do not need to be repeatedly called when the size of the collection is essays on wilderness survival, known. Use collection.size() and a loop counter instead. Cover. Avoid accessing collection data through the data access methods by implementing a query in the collection class. Elminate repeated casts by decision support case, casting once and cover holding the cast item in a correctly typed variable. Reimplement the collection class to specialize for the data being held in clinical decision support system, the collection. Reimplment the Map class to letter, use a hash function which is more efficient for the data being mapped. Optimizing hash functions: generating a perfect hash function (Page last updated January 2001, Added 2001-02-21, Author Jack Shirazi, Publisher OnJava). Tips: perfect hash functions guarantee that every key maps to a separate entry in a hashtable, and so provide more efficient hastable implementations than generic hash functions. perfect hash functions are possible when the key data is restricted to a known set of elements. Optimize Map implementations by specializing the types of internal datastructures, and method parameter types and return types.
Optimize Map implementations by using a specialized hash function that is optimized for the key type, rather than generic to effect essay computer, all possible types of cover, keys. What On Spring Break Essay. Generate a perfect hash function using some variable combination of simple arithmentic operators. Perfect hash functions may require excessive amounts of memory. Minimal perfect hash maps do not require any excess memory, but may impose significant overheads on the map. Microtuning (Page last updated March 2002, Added 2002-03-25, Author Jack Shirazi, Publisher OnJava). Tips: Performance is dependent on data as well as code. Different data can make identical code perform very differently. Always start tuning with a baseline measurement.
The System.currentTimeMillis() method is the most basic measuring tool for tuning. You may need to repeatedly call a method in cafe letter, order to on spring essay, reliably measure its average execution time. Cafe Cover Letter. Minimize the cause effect essay addiction, possibility that CPU time will be allocated to anything other than the cafe cover letter, test while it is and fitness generation, running by ensuring no other processes are runing during the test, and that the test remains in cover, the foreground. Eb White Lake. Baseline measurements normally show some useful information, e.g. the cafe letter, average execution time for essay on technology in younger, one call to a method. Multiplying the average time taken to execute a method or sequence of methods, by the number of cafe, times that sequence will be called in a time period, gives you an estimate of the fraction of the total time that the sequence takes.
There are three routes to tuning a method: Consider unexpected differences in different test runs; Analyze the algorithm; Profile the method. What. Creating an cafe cover letter exception is a costly procedure, because of filling in on wilderness, stack trace. A profiler should ideally be able to take a snapshot of performance between two arbitrary points. Tuning is an iterative process: you normally find one bottleneck, make changes that improve performance, test those changes, and letter then start again. What Break. Algorithm changes usually provide the best speedup, but can be difficult to cafe cover, find. Examining the code for the causes of the essays on wilderness, differences in speed between two variations of cafe, test runs can be useful, but is restricted to those tests for once more, which you can devise alternatives that show significant timing variations.
Profiling is always an option and almost always provides something that can be speeded up. But the law of diminishing returns kicks in after a while, leaving you with bottlenecks that are not worth speeding up, because the potential speedup is too small for the effort required. Letter. Generic integer parsing (as with the Integer constructors and methods) may be overkill for converting simple integer formats. Simple static methods are probably best left to be inlined by the JIT compiler rather than by cause effect computer, hand. String.equals() is letter, expensive if you are only essay more, testing for an empty string. It is quicker to cafe cover, test if the length of the string is once more, 0. Set a target speedup to reach. With no target, tuning can carry on for much longer than is needed. A generic tuning procedure is: Identify the cafe letter, bottleneck; Set a performance target; Use representative data; Measure the on technology in younger, baseline; Analyze the cover letter, method; Test the change; Repeat. Efficiently formatting doubles (Page last updated December 2000, Added 2000-12-20, Author Jack Shirazi, Publisher OnJava).
Tips: Double.toString(double) is slow. Essay And Fitness. It needs to letter, process more than you might think, and does more than you might need. Essays Survival. Proprietary conversion algorithms can be significantly faster. One such algorithm is presented in the article. Converting integers to strings can also be faster than the SDK. Cafe. An algorithm successively stripping off the highest is used in clinical, the article. Formatting numbers using java.text.DecimalFormat is always slower than Double.toString(double), because it first calls Double.toString(double) then parses and cafe letter converts the result. Essays On Wilderness Survival. Formatting using a proprietary conversion algorithm can be faster than any of the methods discussed so far, if the number of digits being printed is not large. The actual time taken depends on the number of digits being printed.
Multiprocess JVMs (Page last updated September 2001, Added 2001-10-22, Author Jack Shirazi, Publisher OnJava). Tips: Using or implementing a multiprocess framework to combine Java processes into one JVM can save on memory space overheads and reduce startup time. Measuring JDBC performance (Page last updated December 2001, Added 2001-12-26, Author Jack Shirazi, Publisher OnJava). Tips: Effectively profiling distributed applications can be difficult. Cover Letter. I/O can show up as significant in profiling, simply because of the nature of a distributed application. It can be unclear whether threads blocking on essay in younger reads and writes are part of a significant bottleneck or simply a side issue. When profiling, it is usually worthwhile to have separate measurements available for the communication subsystems. Wrapping the cafe letter, JDBC classes provides an effective technique for survival, measuring database calls. [Article discusses how to create JDBC wrapers to measure the performance of database calls]. If more than a few rows of letter, a query are being read, then the ResultSet.next() method can spend a significant amount of time fetching rows from the database, and this time should be included in measurements of research and science, database access. JDBC wrappers are simple and robust, and require very little alteration to the application using them (i.e, are low maintenance), so they are suitable to cover, be retained within a deployed application.
Catching OutOfMemoryErrors (Page last updated August 2001, Added 2001-10-22, Author Jack Shirazi, Publisher OnJava). Tips: -Xmx and -Xms (-mx and -ms) specify the heap max and starting sizes. Research Paper. Runtime.totalMemory() gives the current process size, Runtime.maxMemory() (available from SDK 1.4) gives the cover letter, -Xmx value. Repeatedly allocating memory by creating objects and holding onto them will expand the process to its maximum possible size. This technique can also be used to flush memory. If a process gets too large, the operating system will start paging the process causing a severe decrease in performance. What I Did Break. It is reasonable to catch the OutOfMemoryError if you can restore your application to a known state that can proceed with processing. For example, daemon service threads can often do this. The RandomAccess interface. (Page last updated October 2001, Added 2001-11-27, Author Jack Shirazi, Publisher OnJava). Tips: A java.util.List object which implements RandomAccess should be faster when using List.get() than when using Iterator.next(). Use instanceof RandomAccess to test whether to use List.get() or Iterator.next() to traverse a List object. [Article describes how to cafe, guard the test to support all versions of case, Java].
Whoopee!! A non-blocking I/O library for Java. This is the single most important functionality missing from the SDK for scalable server applications. The important class is SelectSet which allows you to multiplex all your i/o streams. Cafe. If you want a scalable server and can use this class then DO SO. NOTE THAT SDK 1.4 WILL INCLUDE NON_BLOCKING I/O (Page last updated March 2001, Added 2001-01-19, Author Matt Welsh, Publisher Welsh). Tips: [The system select(2)/poll(2) functions allow you to take any collection of i/o streams and eb white essay once lake ask the operating system to check whether any of them can execute read/write/accept without blocking. Letter. The system call will block if requested until any one of the i/o streams is essay on technology and fitness, ready to execute. Before Java, no self-respecting server would sit on multiple threads in blocked i/o mode, wasting thread resources: instead select/poll would have been used.] For years, Jonathan Hardwick's old but classic site was the cafe cover, only coherent Java performance tuning site on the web.
He built it while doing his PhD. On Wilderness. It wasn't updated beyond March 1998, when he moved to letter, Microsoft, but most tips are still useful and valid. Essay Once. The URL is for cover letter, the top page, there are another eight pages. Thanks Jonathan. On Technology And Fitness. (Page last updated March 1998, Added 2000-10-23, Author Jonathan Hardwick, Publisher Hardwick). Cafe. Tips: Don't optimize as you go. Write your program concentrating on clean, correct, and understandable code. Use profiling to find out where that 80% of execution time is going, so you know where to concentrate your effort. Always run before and essays on wilderness after benchmarks.
Use the right algorithms and data structures. Compile with optimization flag, javac -O. Cover. Use a JIT. Multithread for multi-processor machines. Use clipping to what break, reduce the amount of work done in repaint() Use double buffering to improve perceived speed. Use image strips or compression to speed up downloading times.
Animation in Java Applets from JavaWorld and Performing Animation from cafe, Sun are two good tutorials. Use high-level primitives; it's much faster to call drawPolygon() on a bunch of points than looping with drawLine(). If you have to draw a single pixel drawLine (x,y,x,y) may be faster than fillRect (x,y,1,1). Use Buffered I/O classes. Avoid synchronized methods if you can. And Science. Synchronizing on methods rather than on code blocks is slightly faster. Use exceptions only where you really need them. Use StringBuffer instead of +. Cover Letter. Use System.arraycopy() and any other optimized API's available from the SDK. Replace the essay more, generic standard classes with faster implementations specific to the application. Create subclasses to override methods with faster versions.
Avoid expensive constructs and data structures, e.g. one-dimensional array is faster than a two-dimensional array. Use the faster switch bytecode. Use private and static methods, and final classes, to cafe cover letter, encourage inlining by essay and fitness generation, the compiler. Reuse objects. Local variables are the faster than instance variables, which are in turn faster than array elements. ints are the fastest data type. Cafe Cover. Compiler optimizations: loop invariant code motion; common subexpression elimination; strength reduction; variable allocation reassignment. Decision Support System Case. Use java -prof or other profiler. Cafe Cover Letter. Use a timing harness to run benchmarks. What On Spring Break Essay. Use a memory measurement harness to run benchmarks.
Call system.gc() before every timing run to minimize inconsistent results due to garbage collection in the middle of cafe cover, a run. Use JAR or zip files. If size is a constraint: use SDK classes wherever possible; inherit whatever possible; put common code in one place; initialize big arrays at runtime by parsing a string; use short names; Balancing Network Load with Priority Queues (Page last updated December 2001, Added 2002-02-22, Author Frank Fabian, Publisher Dr. Dobb's).
Tips: Hardware traffic managers redirect user requests to a farm of servers based on survival server availability, IP address, or port number. All traffic is routed to the load balancer, then requests are fanned out to servers based on the balancing algorithm. Popular load-balancing algorithms include: server availability (find a server with available processing capability); IP address management (route to the nearest server by IP address); port number (locate different types of servers on different machines, and route by port number); HTTP header checking (route by URI or cookie, etc). Web hits should cater for handling peak hit rate, not the average rate. Letter. You can model hit rates using gaussian distribution to determine the average hit rate per time unit (e.g. per what essay second) at peak usage, then a poisson probability gives the probability of a given number of users simulatneously hitting the server within that time unit. [Article gives an cafe example with gaussian fitted to peak traffic of 4000 users with a standard deviation of on technology and fitness in younger generation, 20 minutes resulting in letter, an average of 1.33 users per on technology generation second at the peak, which in cover letter, turn gives the probabilities that 0, 1, 2, 3, 4, 5, 6 users hitting the server within one second as 26%, 35%, 23%, 10%, 3%, 1%, 0.2%.
Service time was 53 milliseconds, which means that the essays on wilderness, server can service 19 hits per second without the service rate requiring requests being queued.] System throughput is the arrival rate divided by the service rate. Letter. If the ratio becomes greater than one, requests exceed the what on spring, system capability and will be lost or need to be queued. Cafe Cover Letter. If requests are queued because capacity is exceeded, the throughput must drop sufficiently to eb white essay more to the, handle the queued requests or the system will fail (the service rate must increase or arrival rate decrease). If the letter, average throughput exceeds 1, then the system will fail. Sort incoming requests into different priority queues, and service the requests according to the priorities assigned to essay, each queue. Cover. [Article gives the example where combining user and automatic requests in one queue can result in a worst case user wait of 3.5 minutes, as opposed to eb white to the, less than 0.1 seconds if priority queues are used]. [Note that Java application servers often do not show a constant service time. Instead the cover, service time often increases with higher concurrency due to non-linear effects of garbage collection].
Cutting Edge Java Game Programming. And Fitness In Younger Generation. Oldish but still useful intro book to games programming using Java. Cafe. (Page last updated 1996, Added 2001-06-18, Author Neil Bartlett, Steve Simkin , Publisher Coriolis). Tips: AWT components are not useful as game actors (sprites) as they do not overlap well, nor are they good at research paper and science being moved around the screen. Celled image files efficiently store an cafe letter animated image by dividing an image into a rectangular grid of cells, and allocating a different animation image to effect essay addiction, each cell. A sequence of similar images (as you would have for an animation) will be stored and transferred efficiently in most image formats.
Examining pixels using PixelGrabber is slow. drawImage() can throw away and re-load images in response to memory requirements, which can make things slow. Letter. Pre-load and pre-scale images before using them to get a smoother and faster display. Clinical Support System Study. The more actors (sprites), the more time it takes to draw and the slower the game appears. Use double-buffering to letter, move actors (sprites), by redrawing the actor and support system background for the relevant area. Redraw speed depends on: how quickly each object is drawn; how many objects are drawn; how much of each object is drawn; the total number of drawing operations. You need to cover, reduce some or all of these until you get to about 30 redraws per second. Clinical Decision System Study. Don't draw actors or images that cannot be seen. If an actor is not moving then incorporate the actor as part of the background. Cafe Letter. Only redraw the area that has changed, e.g. the old area where an research paper and science actor was, and cafe the new area where it is.
Redrawing several small areas is essay on technology in younger, frequently faster than drawing one large area. For the cover letter, redraws, eliminate overlapping areas and merge adjacent (close) areas so that the number of redraws is kept to a minimum. What I Did On Spring. Put slow and cafe fast drawing requirements in separate threads. Bounding-box detection can use circles for lake, the bounding box which requires a simple radii detection. Load sounds in a background thread.
Make sure you have a throttle control that can make the game run slower (or pause) when necessary. The optimal network topology for network games depends on the number of users. If the cafe, cumulative downloading of your applet exceeds the player?s patience, you?ve lost a customer. The user interface should always be responsive. A non-responsive window means you will lose your players. Give feedback on necessary delays. Provide distractions when unavoidable delays will be lengthy [more than a few seconds]. Essays On Wilderness Survival. Transmission time varies, and is always slow compared to operations on the local hardware. Cafe Letter. You may need to paper on religion, decide the letter, outcome of the action locally, then broadcast the more, result of the action.
This may require some synchronization resolution. Latency between networked players can easily lead to de-synchronized action and player frustration. Displays should locally simulate remote action as continuing current activities/motions, until the display is cafe cover letter, updated. On update, the actual current situation should be smoothly resolved with the simulated current situation. Essay In Younger. Sending activity updates more frequently ensures smoother play and better synchronization between networked players, but requires more CPU effort and so affects the local display. In order to cafe letter, avoid adversely affecting local displays, send actvity updates from a low priority thread. Discard any out-of-date updates: always use the latest dated update. A minimum broadcast delay of one-third the average network connection travel time is appropriate.
Once you exceed this limit, the additional traffic can cause more grief than benefit. Clinical Decision Support Study. Put class files into a (compressed) container for network downloading. Cover Letter. Avoid repeatedly evaluating invariant expressions in a loop. Take advantage of inlining where possible (using final, private and static keywords, and compiling with javac -O) Profile the code to determine the expensive methods (e.g. Essay Computer. using the -prof option) Use a dissassembler (e.g. like javap) to determine which of various alternative coding formulations produces smaller bytecode. To reduce the number of cover letter, class files and essay on technology in younger generation their sizes: use the SDK classes as much as possible; and implement common functionality in one place only.
To optimize speed: avoid synchronized methods; use buffered I/O; reuse objects; avoid unnecessary screen painting. Cafe Cover Letter. Raycasting is faster than raytracing. Raycasting maps 2D data into a 3D world, drawing entire vertical lines using one ray. Use precalculated values for once more lake, trignometric and other functions, based on the angle increments chosen for cover letter, your raycasting. In the absence of a JIT, the polygon drawing routines fron the AWT are relatively efficient (compared to array manipulation) and may be faster than texture mapping. What Essay. Without texture mapping, walls can be drawn faster with one call to fillPolygon (rather than line by line). An exponential jump search algorithm can be used to cafe, reduce ray casts - by quickly finding boundaries where walls end (like a binary search, but double increments until your overshoot, then halving increments from the last valid wall position). It is paper and science, usually possible to increase performance at the expense of cover, image quality and clinical support case study accuracy.
Techniques include reducing pixel depth or display resolution, field interlacing, aliasing. The key, however, is to degrade the image in a way that is cover, likely to be undetectable or unnoticeable to the user. Essays On Wilderness. For example a moving player often pays less attention to image quality than a resting or static player. Use information gathered during the rendering of one frame to approximate the geometry of the next frame, speeding up its rendering. If the geometry and content is not too complicated, binary space partition trees map the view according to what the player can see, and can be faster than ray casting. Designing remote interfaces (Page last updated March 2001, Added 2001-04-20, Author Brian Goetz, Publisher JavaWorld). Cover Letter. Tips: Remote object creation has overheads: several objects needed to support the remote object are also created and manipulated. Remote method invocations involve a network round-trip and marshalling and unmarshaling of parameters. Survival. This adds together to impose a significant latency on remote method invocations.
Different object parameters can have very different marshalling and unmarshaling costs. A poorly designed remote interface can kill a program's performance. Cafe Letter. Excessive remote invocation network round-trips are a huge performance problem. Calling a remote method that returns multiple values contained in a temporary object (such as a Point), rather than making multiple consecutive method calls to retrieve them individually, is paper on religion and science, likely to be more efficient. (Note that this is cafe letter, exactly the opposite research on religion of the advice offered for good performance of cover letter, local objects.) Avoid unnecessary round-trips: retrieve several related items simultaneously in one remote invocation, if possible. Avoid returning remote objects when the caller may not need to hold a reference to the remote object. Survival. Avoid passing complex objects to remote methods when the remote object doesn't necessarily need to cafe cover, have a copy of the research, object.
If a common high-level operation requires many consecutive remote method calls, you need to revisit the class's interface. A naively designed remote interface can lead to an application that has serious scalability and performance problems. [Article gives examples showing the effect of applying the listed advice]. Glen McCluskey's paper with 30 tuning tips, now free. Cafe. (Page last updated October 1999, Added 2000-10-23, Author Glen McCluskey, Publisher McCluskey). Tips: Faster algorithms are better. On Wilderness. Different architectures can be functionally identical but perform very differently. Keep performance in mind at the design stage. Use the fastest available JVM.
Use static variables for cafe cover, fields that only need to be assigned once. Reuse objects where reasonable, e.g. nodes of a linked list. What I Did. Inline methods manually where appropriate. Cafe. [Better to decision support case study, use a preprocessor]. Keep methods short and simple to make them automatic inlining candidates. final classes can be faster. Cover Letter. Synchronized methods are slower than the to the lake, identical non-synchronized one. Consider using non-synchronized classes and synchronized-wrappers. Access to private members of inner classes from the enclosing class goes by a method call even if not intended to. Use StringBuffer instead of the '+' String concatentation operator. Use char arrays directly to create Strings rather than StringBuffers. '==' is faster than equals(). Cover. intern() Strings to enable identity (==) comparisons. Eb White Essay To The. Convert strings to char arrays to process characters, rather than accessing characters one at letter a time using String.charAt().
Creating Doubles from essays on wilderness survival, strings is slow. Buffer i/o. MessageFormat is slow. Reuse objects. File information such as File.length() requires a system call and can be slow.
Use System.arraycopy() to copy arrays. Cover. ArrayList is faster than Vector. On Spring Break Essay. Preset array capacity to as large as will be required. LinkedList is faster than ArrayList for inserting elements to the front of the array, but slower at cafe cover indexed lookup. Program using interfaces so that the essay, actual structure can be easily swapped to improve performance. Use the cafe letter, -g:none option to the javac compiler. Essays On Wilderness Survival. Primitive data wrapper classes (e.g. Cover. Integer) are slower than using the eb white essay once more, primitive data directly. Null out letter references when they are no longer used so that garbage collection can reclaim their space. Use SoftReferences to once more, recycle memory when required.
BitSets have deterministic memory requirements where boolean arrays do not (booleans are implemented as bytes rather than bits in some JVMs). Cover Letter. Use sparse arrays to hold widely spaced indexable data. Performance tuning part of a white paper about Java on Solaris 2.6. (Page last updated 2000, Added 2000-10-23, Author ?, Publisher Sun). Tips: To profile I/O calls, use a profiler or use truss and look for generation, read() and write() system calls. Buffer I/O. Cafe Cover. Tune the cause effect computer addiction, buffer size (bigger is cover letter, usually better if memory is available). Essay On Technology And Fitness Generation. Use char arrays for all character processing in loops, rather than using the cafe cover letter, String or StringBuffer classes. Avoid character processing using methods (e.g. Cause Effect Computer Addiction. charAt(), setCharAt()) inside a loop.
Set the initial StringBuffer size to the maximum string length, if it is known. Cafe. StringTokenizer is very inefficient, and on wilderness can be optimized by storing the cafe cover, string and delimiter in a character array instead of in String, or by storing the highest delimiter character to allow a quicker check. Accessing arrays is much faster than accessing vectors, String, and StringBuffer. Use System.arraycopy() to improve performance. Vector is convenient to use, but inefficient. Ensure that elementAt() is not used inside a loop. FastVector is faster than Vector by making the elementData field public, thus avoiding (synchronized) calls to elementAt().
Use double buffering and override update() to improve screen painting and drawing. Use custom LayoutManagers. Repaint only the damaged regions (use ClipRect). Effect Essay Computer Addiction. To improve image handling: use MediaTracker; use your own imageUpdate() method; pre-decode and store the image in cafe cover letter, an array - image decoding time is effect computer addiction, greater than loading time. Pre-decoding using PixelGrabber and MemoryImageSource should combine multiple images into one file for maximum speed. Increase the initial heap size from the 1-MByte default with -ms and -mx [-Xms and -Xmx]. Use -verbosegc.
Take size into account when allocating arrays (for instance, if short is big enough, use it instead of int. Avoid allocating objects in loops (readLine() is a common example). Minimize synchronization. Polling is only acceptable when waiting for outside events and cafe should be performed in a side thread. Use wait/notify instead. Move loop invariants outside the loop. Make tests as simple as possible. Perform the loop backwards (this actually performs slightly faster than forward loops do). Essay Once To The Lake. [Actually it is converting the test to compare against 0 that makes the difference]. Use only local variables inside a loop; assign class fields to local variables before the loop.
Move constant conditionals outside loops. Cover Letter. Combine similar loops. Nest the once more lake, busiest loop, if loops are interchangeable. Unroll the loop, as a last resort. Convert expressions to cover letter, table Lookups. In Younger. Use caching. Pre-compute values or delay evaluation to shift calculation cost to cover letter, another time. [Also gives information on research paper on religion using Solaris Trace Normal Format (TNF) utilities for profiling java applications].
Detailed article on cafe cover letter load testing systems (Page last updated January 2001, Added 2001-01-19, Author Himanshu Bhatt, Publisher Java Report). Essay Addiction. Tips: Internet systems should be load-tested throughout development. Cafe Letter. Load testing can provide the basis for: Comparing varying architectural approaches; Performance tuning; Capacity planning. Initially you should identify the probable performance and scalability based on the requirements. You should be asking about: numbers of research, users/components; component interactions; throughput and transaction rates; performance requirements. Factor in batch requirements and letter performance characteristics of dependent (sub)systems. Note that additional layers, like security, add overheads to performance.
Logging and stateful EJB can degrade performance. After the initial identification phase, the target should be for a model architecture that can be load-tested to support case study, feedback information. Scalability hotspots are more likely to exist in the tiers that are shared across multiple client sessions. Performance measurements should be from presentation start to presentation completion, i.e. Cover. user clicks button (start) and information is displayed (completion). Use load-test suites and frameworks to perform repeatable load testing. Article on using syslog to track performance across distributed systems (Page last updated December 2000, Added 2001-01-19, Author Brian Maso, Publisher DevX). Tips: Use syslog to log distributed system performance. Make sure you instrument distributed systems so that you do get performance logging.
JDBC Performance Tips (targeted at survival AS/400, but generically applicable) (Page last updated February 2001, Added 2001-03-21, Authors Richard Dettinger and Mark Megerian, Publisher IBM). Tips: Move to the latest releases of Java as they become available. Use prepared statements (PreparedStatement class) [article provides coded example of using Statement vs. PreparedStatement]. Cafe Cover. Note that two database calls are made for each row in a ResultSet: one to describe the column, the second to tell the db where to put the data.
PreparedStatements make the description calls at construction time, Statements make them on every execution. Avoid retrieving unnecessary columns: don't use SELECT *. If you are not using stored procedures or triggers, turn off autocommit. What. All transaction levels operate faster with autocommit turned off, and doing this means you must code commits. Coding commits while leaving autocommit on will result in extra commits being done for every db operation. Use the appropriate transaction level. Cover Letter. Increasing performance costs for cause computer addiction, transaction levels are: TRANSACTION_NONE; TRANSACTION_READ_UNCOMMITTED; TRANSACTION_READ_COMMITTED; TRANSACTION_REPEATABLE_READ; TRANSACTION_SERIALIZABLE. Note that TRANSACTION_NONE, with autocommit set to true gives access to cafe cover, triggers, stored procedures, and large object columns.
Store string and char data as Unicode (two-byte characters) in the database. Avoid expensive database query functions such as: getBestRowIdentifier; getColumns; getCrossReference; getExportedKeys; getImportedKeys; getPrimaryKeys; getTables; getVersionColumns. What I Did. Use connection pooling, either explicitly with your own implementation, or implicitly via a product that supports connection pooling. Use blocked fetchs (fetching table data in blocks), and tailor the block size to reduce calls to cafe letter, the database, according to the amount of data required. Use batch updates (sending multiple rows to essay on technology and fitness generation, the database in one call). Cafe Cover. Use stored procedures where appropriate. Cause Effect Computer. These benefit by reducing JDBC complexity, are faster as they use static SQL, and move execution to the server and potentially reduce network trips. Use the type-correct get() method, rather than getObject(). Patrick Killelea's Java performance tips. (Page last updated 1999, Added 2000-10-23, Author Patrick Killelea, Publisher Killelea). Tips: System.currentTimeMillis may take up to 0.5 milliseconds to cafe, execute.
The architecture and algorithms of your program are much more important than any low-level optimizations you might perform. Tune at the highest level first. Make the decision system, common case fast (Amdahl's advice). Use what you know about the runtime platform or usage patterns. Look at a supposedly quiet system to see if it's wasting time even when there's no input. Keep small inheritance chains. Use stack (local) variables in cafe cover, preference to class variables. Merge classes. drawPolygon() is faster than using drawLine() repeatedly. Don't create too may objects. Reuse objects if possible. Beware of object leaks (references to objects that are never nulled).
Accessor methods increase overhead. Research On Religion And Science. Compound operators such as n += 4; are faster than n = n + 4; because fewer bytecodes are generated. Shifting by cafe cover, powers of two is faster than multiplying. Survival. Multiplication is faster than exponentiation. int increments are faster than byte or short increments. Floating point increments are much slower than any integral increment. Memory access from better to worse: local vars; supersuperclass instance variable; superclass instance var; class instance var; class static var; array elements. It can help to copy slower-access vars to fast local vars if you are going to operate on them repeatedly, as in cafe cover, a loop. Use networking timeouts, TCP_NODELAY, SO_TIMEOUT, especially in case of dying DNS servers. Buffer network io. [or read explicitly in chunks]. Avoid reverse DNS where you can. Use UDP rather than TCP if speed is more important than accuracy.
Use threads. Prioritize threads. Use notify instead of notifyAll. Use synchronization sparingly. Counting down is often faster than counting up. [the loop test comparison to 0 is what matters]. Keep synchronized methods out of what break, loops if you possibly can. Avoid excessive String manipulation. Use String Buffers or Arrays rather than String. byte arrays may be faster than StringBuffers for certain operations, especially if you use System.arraycopy(). Cafe. Use StringBuffer rather than the + operator. Eb White Essay Once More To The Lake. Watch out for slow fonts, Fonts vary in speed of rendering. Keep the paint method small.
It will get called a lot. Double buffer where possible. For some applications that access the cafe, date a lot, it can help to set the local timezone to paper on religion and science, be GMT, so that no conversion has to take place. Cafe Letter. Potential compiler optimizations: loop invariant code motion; common subexpression elimination; strength reduction; variable allocation. On Technology And Fitness Generation. Don't turn off native threads. Use .jar files.
Rewrite Java library classes to make them smaller or instantiate fewer objects or eliminate synchronization. Install classes locally. Tutorial on the full screen capabilities in cover letter, the 1.4 release (5 pages plus example pages under the top page) (Page last updated June 2001, Added 2001-06-18, Author Michael Martak, Publisher Sun). Tips: The full-screen exclusive mode provides maximum image display and drawing performance by allowing direct drawing to the screen. Use java.awt.GraphicsDevice.isFullScreenSupported() to determine if full-screen exclusive mode is available. If it is not available, full-screen drawing can still be used, but better performance will be obtained by using a fixed size window in normal screen mode. Full-screen exclusive applications should not be resizable. Turn off decoration using the setUndecorated() method. Change the research paper on religion and science, screen display mode (size, depth and refresh rate), to the best match for your image bit depth and display size so that scaling and other image alterations can be avoided or minimized.
Don't define the letter, screen painting code in the paint() method called by the AWT thread. Define your own rendering loop for screen drawing, to be executed in research paper on religion, any thread other than the AWT thread. Use the setIgnoreRepaint() method on your application window and letter components to turn off all paint events dispatched from the operating system completely, since these may be called during inappropriate times, or worse, end up calling paint, which can lead to race conditions between the AWT event thread and your rendering loop. Do not rely on essay on technology and fitness generation the update or repaint methods for delivering paint events. Do not use heavyweight components, since these will still incur the overhead of involving the AWT and cafe cover letter the platform's windowing system. Eb White Once More To The. Use double buffering (drawing to an off-screen buffer, then copying the finished drawing to the screen). Cafe Cover Letter. Use page-flipping (changing the video pointer so that an off-screen buffer becomes the on-screen buffer, with no image copying required). Clinical System Case Study. Use a flip chain (a sequence of off-screen buffers which the video pointer successively points to one after the other). java.awt.image.BufferStrategy provides getDrawGraphics() (to get an off-screen buffer) and show() (to display the buffer on screen). Use java.awt.BufferCapabilities to customize the BufferStrategy for optimizing the performance of your application.
If you use a buffer strategy for double-buffering in cafe cover letter, a Swing application, you probably want to turn off double-buffering for your Swing components, Multi-buffering is only useful when the drawing time exceeds the time spent to do a show. Research Paper. Don't make any assumptions about performance: profile your application and identify the bottlenecks first. HP Java tuning site, including optimizing Java and optimizing HPUX for Java. This is the top page, but several useful pages lie off it (tips extracted for inclusion below). Includes a nice procedure list for tuning apps, and some useful forms for what you should record while tuning. (Page last updated 2000, Added 2000-10-23, Author ?, Publisher HP). Cover. Tips: Have a performance target.
Consider architecture and components for bottlenecks. Third-party components may have options that cause bottlenecks. Having debugging turned on can cause performance problems. Having logging turned on can cause performance problems. Is the underlying machine powerful enough. Carefully document any tests and changes.
Create a performance baseline. Make one change at a time. Be careful not to lose a winning tune because it's hidden by a bad tune made at the same time. Record all aspects of the system (app/component/version/version date/dependent software/CPU/Numbers of CPUs/RAM/Disk space/patches/OS config/etc.) Give the decision study, JVMs top system priority. Cafe Cover. Tune the heap size (-mx, -ms options) and i did break essay use -verbosegc to minimize garbage collection impact. A larger heap reduces the frequency of garbage collection but increases the length of time that any particular garbage collection takes.
Rules of thumbs are: 50% of free space available after a gc; set the maximum heap size to be 3-4 times the space required for the estimated maximum number of cafe, live objects; set the initial heap to size a little below the space required for on technology in younger generation, the average data set, and the maximum value large enough to handle the largest data set; increase -Xmn for applications that create many short-lived objects [is -Xmn a standard option?]. [These rules of thumb should only be considered as starting points. Cover. Ultimately you need to tune the VM heap empirically, i.e. by trial and error]. Essays Survival. You may need to cafe, add flags to third party products running in the JVM to eliminate explicit calls to garbage collect (VisiBroker has this known problem). Watch out for bottlenecks introduced from third party products. Make sure you know and use the options available, many of which can affect performance (for better or worse). Essay And Fitness In Younger. Document the changes you make so that you will be able to reproduce the performance. computationally intensive applications should increase the number of CPUs to increase overall system performance and throughput. Cover. Be certain that the essays, application's CPU usage is a factor limiting performance: often, highly contended locks and garbage collections that are too frequent will make the system look busy, but little work is done by the application. [Some nice detailed description on how to profile and analyze application problems, from the HP system and JVM level at http://www.devresource.hp.com/JavaATC/JavaPerfTune/symptoms_solutions.html.] J2EE Application server performance (Page last updated April 2001, Added 2001-04-20, Author Misha Davidson, Publisher Java Developers Journal). Tips: Good performance has sub-second latency (response time) and hundreds of cafe cover, (e-commerce) transactions per second.
Avoid n-way database joins: every join has a multiplicative effect on the amount of work the database has to do. The performance degradation may not be noticeable until large datasets are involved. What On Spring Essay. Avoid bringing back thousands of rows of cafe, data: this can use a disproportionate amount of essays survival, resources. Cache data when reuse is likely. Avoid unnecessary object creation. Minimize the use of synchronization. Cafe. Avoid using the SingleThreadModel interface for essay on technology generation, servlets: write thread-safe code instead. ServletRequest.getRemoteHost() is very inefficient, and can take seconds to complete the reverse DNS lookup it performs. OutputStream can be faster than PrintWriter. JSPs are only generally slower than servlets when returning binary data, since JSPs always use a PrintWriter, whereas servlets can take advantage of a faster OutputStream. Excessive use of custom tags may create unnecessary processing overhead.
Using multiple levels of letter, BodyTags combined with iteration will likely slow down the processing of the page significantly. Use optimistic transactions: write to the database while checking that new data is not be overwritten by on technology in younger generation, using WHERE clauses containing the old data. However note that optimistic transactions can lead to worse performance if many transactions fail. Cafe. Use lazy-loading of dependent objects. For read-only queries involving large amounts of data, avoid EJB objects and use JavaBeans as an system intermediary to access manipulate and store the data for JSP access. Letter. Use stateless session EJBs to cache and manage infrequently changed data. Update the EJB occasionally.
Use a dedicated session bean to perform and cache all JNDI lookups in a minimum number of requests. And Fitness. Minimize interprocess communication. Letter. Use clustering (multiple servers) to increase scalability. Using the Syslog class for logging (Page last updated April 2001, Added 2001-04-20, Author Nate Sammons, Publisher JavaWorld). Tips: Use Syslog to log system performance. Cause Computer Addiction. Logging should not take up a significant amount of the system's resources nor interfere with its operation. Use static final boolean s to letter, wrap logging statements so that they can be easily turned off or eliminated.
Beware of logging to slow external channels. These will slow down logging, and hence the application too. Glen McCluskey's article on tuning Java I/O performance. Weak on serialization tuning. (Page last updated March 1999, Added 2000-10-23, Author Glen McCluskey, Publisher Sun). Tips: Avoid accessing the disk. Avoid accessing the underlying operating system. I Did Break Essay. Avoid method calls. Avoid processing bytes and characters individually. Use buffering either at the class level or at the array level. Disable line buffering.
MessageFormat is slow. Reuse objects. Creating a buffered RandomAccessFile class can be faster than plain RandomAccessFile if you are seeking alot. Compression can help I/O, but only cafe cover, sometimes. Use caching to speed I/O. And Fitness In Younger. Your own tokenizer will be faster than using the available SDK tokenizer. Many java.io.File methods are system calls which can be slow. Designing Entity Beans for cafe cover letter, Improved Performance (Page last updated March 2001, Added 2001-03-21, Author Beth Stearns, Publisher Sun). Tips: Remember that every call of an entity bean method is potentially a remote call.
Designing with one access method per data attribute should only be used where remote access will not occur, i.e. entities are guaranteed to be in the same container. Use a value object which encapsulates all of an entity's data attributes, and which transfers all the essay, data in one network transfer. This may result in large objects being transferred though. Group entity bean data attributes in subsets, and use multiple value objects to provide remote access to those subsets. Performance tuning report in cover letter, German. Thanks to Peter Kofler for what on spring break essay, extracting the tips. (Page last updated November 2001, Added 2001-07-20, Author Sebastian Ritter, Publisher Ritter). Tips: Performance optimizations vary in effect on cafe different platforms. Always test for your platforms. Essay. Reasons not to optimize: can lead to unreadable source code; can cause new errors; optimizations are often compiler/JVM/platform dependent; can lose object orientation. Reasons to optimize: application uses too much memory/processor/I/O; application is unnaceptably slow. Don't optimize before you have at least a functioning prototype and cafe cover letter some identified bottlenecks.
Try to optimize the on religion and science, design first before targeting the cover, implementation. Profile applications. Use the 80/20 rull which suggests that 80% of the work is done in 20% of the code. Target loops in effect essay computer addiction, particular. Monitor running applications to maintain performance. Plan and budget for some resources to optimize the application. Try to have or develop a couple of performance experts. Specify performance in letter, the project requirements, and specify seperate performance requirements for the various layers of the application. Essays On Wilderness. Consider the effects of performance at letter the analysis stage, and include testing of 3rd party tools. Use a benchmark harness to make repeatable performance tests, varying the on technology and fitness in younger generation, number of users, data, etc.
Use profilers and cafe letter logging to measure performance and essay on technology in younger identify performance problems. Optimize the runtime system if the optimization does not require alterations to cover, the application design or implementation. Eb White Essay. Test various JVMs and choose the optimal JVM. JIT compilers are faster but require more memory than interpreter JVMs. HotSpot can provide better performance and a faster startup and maintain a relatively low memory requirement. Design in asynchronous operations so tasks are not waiting for others to finish when they don't need to. use the right VM use the cover, right threading model (native vs. green) use native compilers give more ram to the VM give all ram to short-lived applications to completely avoid GC use alternate/optimizing compilers use the right database driver use direct JDBC drivers expand all JDK classes into the filesystem to increase access to on technology, classes use slot-local variables (1st 128 bit = 4 slots) (applies for interpreters only) use int use Arraylist instead of cover, Vector use own Hashtable implementations for primitives (i.e. int) use caches use object pools avoid remote method calls use callbacks to avoid blocking remote method calls use batching for remote method calls use the flyweight pattern to reduce object creation [The flyweight pattern uses a factory instead of 'new' to research on religion, reuse objects rather than always create new ones]. use the right access modifier: static private final protected public use inlining use shallow hierarchies (to avoid long instantiation chains) use empty default constructors use direct variable access (not recommended, breaks OO) mix model with view (not recommended, breaks OO) use better algorithms remove redundant code optimize loops unroll loops use int as loop counter count/test loops towards 0 use Exception terminated loops for long loops use constants for cafe cover, expressions with known results, e.g. replace x = 3; . (x does not change) . Effect Computer. ; x += 3; with x = 3; . (x does not change) . ; x = 6; move code outside loops how to optimize: 1st check for better algorithms, 2nd optimize loops use shift for *2 and /2 do not initialize with default values (0, null) use char arrays for mutable Strings use arrays instead of collections use the private final modifier use System.arraycopy() to copy arrays use Hashtable keys with fast hashcode() do not use Strings as keys for letter, Hashtables use new Hashtable() instaed of Hashtable.clear() for very large Hashtables inspect JDK source use methods in order: static final instance interface synchronized use own specialized methods instead of JDK's generalized ones avoid synchronization avoid new objects reuse objects use the original instead of overloaded constructors (give default parameters by your own) avoid inner classes use + for effect computer addiction, concenating 2 Strings, use Stringbuffer for concenating more Strings use clone to create new objects (instead of new) use instance.hashcode() to test for equality of intances use native JDK implemented methods (as System.arraycopy()) avoid Exceptions (use Exceptions only for cases with probability 50%, else use error flags) combine multiple small try-catchs to one larger block use Streams instead of Readers, use Reader and Writer only if you need internationalization use buffering for io use EOFException and ArrayOutOfBoundsException for terminating io reading loops use transient fields to speedup serialisation use externalization instead of cafe, serialisation use multiple threads to increase perceived performance use awt instead of essay on technology, swing for speed use swing instead of awt for less memory use super.paint() to initially draw something (i.e. background) to increase perceived performance use your own wrapper for primitives (with setter methods) use Graphics.drawPolygon() (native implemented) instead of several Graphics.drawlines(). use low priority threads to initialize graphic components in the background use synchronized blocks instead of synchronized methods cache (SQL) Statements for DB access use PreparedStatements for DB access.
Accelerating GUI apps (after 1.4) (Page last updated March 2002, Added 2002-04-26, Author Dana Nourie, Publisher Sun). Tips: To add many items to letter, a JComboBox, add them in one go using a Model on a vector, e.g. new JComboBox(new DefaultComboBoxModel(new Vector(allItemsInAnArray)));. This generates only research on religion, one changed event. Perform GUI operations in bulk to minimize the events generated. When initializing or totally replacing the contents of a model, construct a new one instead of reusing the existing one to minimize generated events. Use threads other then the GUI handling thread for long, indeterminate, or repetitive tasks.
VolatileImage allows you to create a hardware-accelerated offscreen image and manage the contents of that image. From 1.4 Swing double-buffers using VolatileImage hardware acceleration to cafe, improve performance. Repaint small regions instead of essays on wilderness, entire sections or screens. Cafe. For instance, when using tables, repaint a single table cell as needed instead of repainting the entire screen or table. EventHandler provides support for on religion and science, dynamically generating event listeners that have a small footprint and can be saved automatically by the persistence scheme. MIDP tips (Page last updated March 2002, Added 2002-04-26, Author Eric Giguere, Publisher Sun). Tips: Make HTTP requests in a background thread. Use an asynchronous messaging model. Use WBXML to compress XML messages.
Article about avoiding creating objects where possible. (Page last updated 1996, Added 2000-10-23, Author Chuck McManis, Publisher JavaWorld). Tips: The mythology surrounding the slowness of garbage-collected systems is cafe letter, just that, myth. I can show that the number of once more, instructions executed is the same whether I call malloc() and free() or I only call malloc() and some other code calls free(). Simple designs can easily run through many unnecessary objects, e.g. data wrapper objects like Integer. Reuse objects where possible. Use -verbosegc to cafe cover, check the essay on technology in younger, impact of garbage collection on your application. The Eight Fallacies of Distributed Computing (Page last updated 2000, Added 2002-03-25, Author Peter Deutsch, Publisher Sun). Tips: The network can fail to deliver at cafe letter any time. Latency is significant. Bandwidth is always limited. Article on designing for performance focusing on interfaces (Page last updated January 2001, Added 2001-02-21, Author Brian Goetz, Publisher JavaWorld).
Tips: Avoid excessive object creation: be wary of object creation inside of tight loops when executing performance-critical code. Performance-conscious programmers avoid excessive use of String. Defining a utility class which is applied to data required by its constructor means that you must create a new object for essays, every piece of data to cafe cover letter, run it on. Instead, do not require data in the constructor. Do not force methods to provide arguments with input in the form that is convenient rather than efficient. For example, don't require that arguments be passed only more, as String objects if a byte array or char array would also be functionally equivalent (try to support all formats, especially the efficient ones). Defining a method signature in cafe cover, terms of an interchange type (the type of object passed from a caller method to the callee method as an argument) reduces the interface's complexity while maintaining its flexibility, but sometimes this simplicity comes at essay and fitness generation the cost of performance. HotSpot FAQ (Page last updated August 2000, Added 2001-02-21, Author ?, Publisher Sun). Tips: HotSpot has a bunch of startup options that may help you configure your VM to go faster.
HotSpot garbage collection parameters can be tuned with -Xincgc, -XX:NewSize, -XX:MaxNewSize and cafe letter -XX:SurvivorRatio(and heap size parameters). Sun recommends you no longer use objects pools [this is rather a sweeping and inappropriate statement. Object pools are still useful even with HotSpot, but presumably not as often as previously]. Essay More To The. Undocumented option -Xconcurrentio may help performance when there are very many threads. It uses a lighter thread synchronization model. Cover Letter. If using few threads, using -XX:+UseBoundThreads and the light weight process threads (LWP) library may improve performance. LWP threads are scheduled by the JVM, system threads have kernel scheduling.
Don't call System.gc(). Warming loops is no longer necessary from HotSpot 2.0 (SDK 1.3). Clinical Decision. HotSpot now supports on-stack-replacement. HotSpot supports -Xrunhprof options and also -Xaprof for object allocation statistics. Integer alignment of generated native code affects its speed [so it is conceivable that adding the odd bytecode could make code faster]. HotSpot can eliminate dead variables and dead code, i.e. variables that are assigned to but never used [in isolated code segments]. The generational-GC per object costs varies depending on the length of life of the object. A different HP tip page on optimizing Java performance, from the HP-UX Programmer's Guide for Java. Cafe Cover Letter. Gives info on HP system performance monitoring too (Page last updated ?, Added 2000-10-23, Author ?, Publisher HP).
Tips: Maximize thread lifetimes and minimize thread creation/destruction cycles. Minimize contention for shared resources. Minimize creation of short-lived objects. Use -verbosegc to eb white essay once to the, monitor garbage collection. Tune the cover letter, applications to minimize the effects of essays on wilderness, garbage collections. Disk I/O should be minimized. Don't do random I/O to read a file serially (RandomAccessFile class). You should use buffered I/O. Complex AWT graphics will slow down your performance. Use the most current version of Java.
Use -mx and -ms to tune the cafe cover, heap size [now -Xms and -Xmx]. Profile the clinical decision system study, code to find bottlenecks. Bill Venners on the right way to optimize (Page last updated May 1998, Added 2000-10-23, Author Bill Venners, Publisher Artima). Tips: Don't optimize until you know you have a problem. Cover Letter. Measure the program before and clinical support system study after your optimization efforts. Profile the program to isolate the code that really matters to performance (10 to 20 percent), and just focus your optimization efforts there. Try to devise a better algorithm Use APIs in a smarter way Use standard code optimization techniques such as strength reduction, common sub-expression elimination, code motion, and loop unrolling. Only as a last resort should you sacrifice good object-oriented, thread-safe design and cafe maintainable code in the name of performance.
Make methods static wherever possible. Avoid creating lots of short-lived objects. Application performance tuning (Page last updated July 2002, Added 2002-07-24, Author Baya Pavliashvili and Kevin Kline, Publisher informIT). Tips: Application performance problems can be caused and decision support study mitigated with any combination of the following areas: Network topology and throughput; Server hardware configuration; client application code; middle-tier components; database communication code; database configuration settings; logical and physical database design; operating system settings; client hardware; overall application architecture. Monitor the application.
Primary statistics worth analyzing are: the number of concurrent users; number of transactions per unit of time; duration of the cover, longest and shortest transactions; and the average response time. Specify the performance targets. Consider using eye candy to distract attention during acceptable short waits. Identify which application tier contains the bottleneck and clinical decision system case study fix that. It might be hardware or software; low-level or architecture. Cover Letter. Prioritize which problems to fix according to the resources available. Object management article (Page last updated November 1999, Added 2000-12-20, Author Dennis M. Sosnoski, Publisher JavaWorld). Survival. Tips: Objects have a space overhead in cafe letter, addition to the space taken by the data held by the object.
Objects have a space overhead in addition to the space taken by the data held by essay addiction, the object. The overhead is dependent on the particular JVM, but there is cover letter, always some. The space overhead is a per object value, so the percentage of overhead decreases with larger objects. If you work with large numbers of once more, small objects, you can use a huge amount of memory simply for overhead. Different JVMs are optimized for cafe, short lived objects or for on spring break essay, long lived objects. Object creation and garbage collection have significant overheads. Providing you're sensible about cafe cover letter creating objects in research paper on religion and science, heavily used code, it's easy to avoid the object churn cycle. The easiest way to reduce object creation in cafe letter, your programs is by using primitive types in place of objects.
Avoid using wrapper classes (for primitive data types, e.g. Integer) as they impose extra overheads. If you're working with a large number of primitive data types, you can avoid the excessive object overhead of wrappers by storing and cause addiction passing values of the underlying primitive types, and only converting the values into the full objects when necessary for use with methods in the class libraries. Avoid convenience classes like Point if you can manage the underlying data directly. Reuse objects where possible.
Use object pools where this is helpful in reusing objects, but be careful that the pool implementation does actually give a performance improvement (dedicated pools within the class can be significantly faster than abstract pool implementations). Implement pools so that the pool does not retain a reference to any allocated object, so that if the object is not returned to cafe letter, the pool, it can still be garbage collected when finished with (thus avoiding memory leaks). Website usability metrics (Page last updated May 2002, Added 2002-07-24, Author Sharon Gaudin, Publisher EarthWeb). Tips: A website must be easy to navigate and have a quick display and response time. Bad navigation metrics include: abandoned shopping carts; first time visitors look at one or two pages and disappear; dead ends require the clinical decision study, back button; less than 5% buy something; any broken links. Good navigation metrics include: three pages or less from wesbite entry to desired information; no streaming video or Flash introductions; multiple ways to reach the required information; up to date search engines; basic compancy and contact info one click away from the homepage. Common issues affecting Web performance (Page last updated June 2002, Added 2002-07-24, Author Drew Robb, Publisher EarthWeb).
Tips: Symptoms of network problems include slow response times, excessive database table scans, database deadlocks, pages not available, memory leaks and high CPU usage. Causes of performance problems can include the application design, incorrect database tuning, internal and external network bottlenecks, undersized or non-performing hardware or Web and cafe letter application server configuration errors. Root causes of performance problems come equally from four main areas: databases, Web servers, application servers and the network, with each area typically causing about a quarter of the paper, problems. Cafe Letter. The most common database problems are insufficient indexing, fragmented databases, out-of-date statistics and faulty application design. Solutions include tuning the what i did, index, compacting the database, updating the database and rewriting the cafe, application so that the database server controls the query process. The most common network problems are undersized, misconfigured or incompatible routers, switches, firewalls and load balancers, and essays on wilderness inadequate bandwidth somewhere along he communication route. The most common application server problems are poor cache management, unoptimized database queries, incorrect software configuration and cafe poor concurrent handling of essays on wilderness, client requests. Cover. The most common web server problems are poor design algorithms, incorrect configurations, poorly written code, memory problems and overloaded CPUs. Having a testing environment that mirrors the essay on technology and fitness, expected real-world environment is very important in achieving good performance. The deployed system needs to letter, be tested and continually monitored.
The smallest Hello World (Page last updated July 2002, Added 2002-07-24, Author Norman Richards, Publisher Java Developers Journal). Tips: [Brilliantly amusing search to make the smallest Hello World program.] Use the -g:none option to strip debugging bytes from classfiles. Most bytes in Java class files are from the constant pool, then the method declarations. The constant pool includes class and method names as well as strings. The Java compiler will insert a default constructor if you don't specify one, but the constructor is only needed if you will create instances.
You can remove the constructor if you will not be creating instances. Most variables and class references used by the code generate entries in the constant pool. Reusing already existing constant pool entries for class/method/variable names reduces the class file size. Article on using smart proxies. (Page last updated November 2000, Added 2001-01-19, Author M. On Spring Break Essay. Jeff Wilson, Publisher JavaWorld). Tips: Use smart proxies to transparently cache data in the client, thus reducing the number of remote calls. Use smart proxies for caching frequently read, seldom-updated data of remote objects. Cover Letter. Use smart proxies to monitor the performance of RMI calls. What. Use smart proxies to cafe cover, prevent returning multiple copies of the same remote object to i did on spring, client code. Paper detailing the Best Practices for cover letter, Developing High Performance Web and Enterprise Applications using IBM's WebSphere. All the tips are generally applicable to servlet/EJB development, as well as other types of support study, server development. (Page last updated September 2000, Added 2001-01-19, Author Harvey W. Gunther, Publisher IBM). Tips: Do not store large object graphs in javax.servlet.http.HttpSession.
Servlets may need to serialize and deserialize HttpSession objects for persistent sessions, and making them large produces a large serialization overhead. Use the tag %@ page session=false% to cafe cover, avoid creating HttpSessions in research paper on religion and science, JSPs. Cafe Letter. Minimize synchronization in Servlets to avoid multiple execution threads becoming effectively single-threaded. Cause Effect Essay Computer. Do not use javax.servlet.SingleThreadModel. Use JDBC connection pooling, release JDBC resources when done, and reuse datasources for JDBC connections. Use the HttpServlet Init method to perform expensive operations that need only be done once. Minimize use of System.out.println.
Avoid String concatenation +=. Access entity beans from session beans, not from letter, client or servlet code. Reuse EJB homes. Support Case Study. Use Read-Only methods where appropriate in entity-beans to avoid unnecessary invocations to store. Use the lowest impact transaction level possible for cover letter, each transaction. The EJB remote programming model always assumes EJB calls are remote, even where this is i did break, not so. Where calls are actually local to the same JVM, try to use calling mechanisms that avoid the remote call. Remove stateful session beans (and any other unneeded objects) when finished with, to avoid extra overheads in case the cover letter, container needs to case, be passivated.
Beans.instantiate() incurs a filesystem check to cafe, create new bean instances. Use new to avoid this overhead. Tuning IBM's WebSphere product. White paper: Methodology for Production Performance Tuning. Only non-product specific Java tips have been extracted here. I Did On Spring Essay. (Page last updated September 2000, Added 2001-01-19, Author Gennaro (Jerry) Cuomo, Publisher IBM). Tips: A size restricted queue (closed queue) allows system resources to cover letter, be more tightly managed than an paper on religion open queue.
The network provides a front-end queue. A server should be configured to cafe letter, use the network queue as its bottleneck, i.e. only accept a request from the network when there are sufficient resources to process the request. This reduces the load on an app server. However, sufficient requests should be accepted to ensure that the app server is working at maximum capacity, i.e. try not to what i did, let a component sit idle while there are still requests that can be accepted even if other components are fully worked. Cafe Cover. Try to clinical decision support case, balance the workload of the various components. [Paper shows a nice throughput curve giving recommended scaling behavior for an server] The desirable target bottleneck is the CPU, i.e. Cafe Cover. a server should be tuned until the CPU is the remaining bottleneck. Research On Religion And Science. Adding CPUs is a simple remedy to this. Use connection pools and cover letter cached prepared statements for database access. Object memory management is essay and fitness in younger generation, particularly important for server applications.
Typically garbage collection could take between 5% and 20% of the server execution time. Garbage collection statistics provide a useful monitor to determine the server's health. Use the verbosegc flag to collect basic GC statistics. GC statistcs to monitor are: total time spent in GC (target less than 15% of cafe cover, execution time); average time per eb white essay GC; average memory collected per cover GC; average objects collected per GC. Clinical System Case Study. For long lived server processes it is particularly important to eliminate memory leaks (references retained to objects and never released). Use -ms and -mx to tune the JVM heap. Cafe Cover. Bigger means more space but GC takes longer. Use the GC statistics to determine the optimal setting, i.e the paper and science, setting which provides the minimum average overhead from GC. The ability to reload classes is typically achieved by testing a filesystem timestamp. This check should be done at set intermediate periods, and not on letter every request as the filesystem check is an once more lake expensive operation.
WebSphere V3 Performance Tuning Guide (Page last updated March 2000, Added 2001-01-19, Authors Ken Ueno, Tom Alcott, Jeff Carlson, Andrew Dunshea, Hajo Kitzh?fer, Yuko Hayakawa, Frank Mogus, Colin D. Cover Letter. Wordsworth, Publisher IBM). Cause Essay Computer. Tips: [The Red book lists and discusses tuning parameters available to Websphere] Run an application server and any database servers on cafe cover letter separate server machines. Research Paper On Religion. JVM heap size: -mx, -ms [-Xmx, -Xms]. As a starting point for a server based on a single JVM, consider setting the maximum heap size to 1/4 the total physical memory on the server and cafe setting the minimum to 1/2 of the maximum heap. Essays Survival. Sun recommends that ms be set to somewhere between 1/10 and cover 1/4 of the mx setting. They do not recommend setting ms and mx to be the same. Bigger is not always better for heap size. In general increasing the size of the Java heap improves throughput to the point where the eb white essay once lake, heap no longer resides in physical memory. Once the letter, heap begins swapping to on religion and science, disk, Java performance drastically suffers. Cafe. Therefore, the mx heap setting should be set small enough to contain the heap within physical memory. Essays On Wilderness Survival. Also, large heaps can take several seconds to fill up, so garbage collection occurs less frequently which means that pause times due to GC will increase.
Use verbosegc to help determine the letter, optimum size that minimizes overall GC. In some cases turning off asynchronous garbage collection (-noasyncgc, not always available to eb white once lake, all JVMs) can improve performance. Setting the JVM stack and cafe native thread stack size (-oss and -ss) too large (e.g. Decision Support. greater than 2MB) can significantly degrade performance. When security is enabled (e.g. Cafe Cover. SSL, password authentication, security contexts and what on spring break access lists, encryption, etc) performance is letter, degraded by significant amounts. One of the most time-consuming procedures of a database application is on wilderness, establishing a connection to the database. Use connection pooling to minimize this overhead. Using a ternary search tree for fast searches of partial text matches (Page last updated February 2001, Added 2001-03-21, Author Wally Flint, Publisher JavaWorld).
Tips: [Article discusses several efficient algorthms for searching through ternary search trees which provide fast partial match searches of character array keys]. When synchronization is required (Page last updated July 2001, Added 2001-07-20, Author Brian Goetz, Publisher IBM). Tips: synchronization means mutual exclusion (if the same monitor is used), atomicity of the cover, synchronized block (again with respect to other threads using the same monitor) and synchronization of in younger, thread memory to cafe letter, main memory. I Did On Spring Essay. Because synchronization synchronizes thread memory with main memory, there is a cost to letter, synchronization beyond simply acquiring a lock. Too little synchronization can lead to corrupt data; too much can lead to reduced performance and deadlock. The costs of on technology and fitness in younger, synchronization vary with JVMs, with more recent JVMs being more efficient. Cover. The costs of synchronization differs depending on whether or not threads are actually contending for locks (more expensive, slower), or for uncontended synchronization where the thread is basically acting in single-threaded mode (cheaper, faster). You need to synchronize or make volatile variables holding data that will be shared between threads. I Did On Spring Break. Composite operations may need synchronizing to cover, make them atomic even if each individual operation is already synchronized. Reducing thread contention (Page last updated September 2001, Added 2001-10-22, Author Brian Goetz, Publisher IBM). Tips: Thread contention impairs scalability because it forces the scheduler to serialize operations, even if a free processor is available.
Analyze your program to and fitness generation, determine where contention is likely to occur. Make synchronized blocks as short as possible. Spread synchronizations over more than one lock. Letter. [Article provides a thread-safe hashed Map implementation with lower global contention than Hashtable.] If you will be acquiring and releasing the same lock many times (such as in a loop), acquire the decision system study, lock before the loop: it is faster to acquire a lock that you already hold than one that nobody holds. J2EE worst practices (Page last updated April 2002, Added 2002-04-26, Author Brett McLaughlin, Publisher OnJava). Tips: The choice of cover, data store type (RDB, ODB, XML-DB, directory-server, etc) affects performance, and should not be made without performance considerations. Directory servers are optimized for support system case, frequent reads, with few writes. If you frequently add data to a directory server, performance degrades. Cafe Letter. Stateless session beans are soooo much faster. The hprof profiler (Page last updated December 2001, Added 2001-12-26, Author Bill Pierce, Publisher JavaWorld). Tips: Use the hprof profiler with the startup command java -Xrunhprof[:help][:suboption=value. ] MyMainClass. [Article describes using hprof and reading the resultant profile files to profile an application for research paper on religion, memory leaks, cpu-bottlenecks and thread contention]. hprof can be used to profile object allocation (heap option), method bottlnecks (cpu option) and cafe letter thread contention (monitor option). Weblogic tuning (generally applicable Java tips extracted) (Page last updated June 2000, Added 2001-03-21, Author BEA Systems, Publisher BEA).
Tips: Response time is i did on spring break essay, affected by: contention and wait times, particularly for shared resources; and cafe cover letter software and hardware component performance, i.e. the amount of time that resources are needed. What I Did On Spring Break Essay. A well-designed application can increase performance by simply adding more resources (for instance, an extra server). Cafe Cover Letter. Use clustered or multi-processing machines; use a JIT-enabled JVM; use Java 2 rather than JDK 1.1; Use -noclassgc. Essay. Use the maximum possible heap size that also is small enough to avoid the JVM from swapping (e.g. 80% of RAM left over after other required processes). Consider starting with minimum initial heap size so that the garbage collector doesn't suddenly encounter a full heap with lots of garbage. Benchmarkers sometimes like to set the heap as high as possible to completely avoid GC for the duration of the benchmark. Distributing the application over several server JVMs means that GC impact will be spread in time, i.e. the various JVMs will most likely GC at different times from each. Cafe. On Java 1.1 the most effective heap size is that which limits the longest GC incurred pause to eb white essay once lake, the longest acceptable pause in processing time.
This will typically require a reduction in the maximum heap size. Too many threads causes too much context switching. Too few threads may underutilize the system. If n=number of cafe, threads, k=number of CPUs, then: (n k) by research on religion and science, a moderate amount of threads is practically ideal; (n k) by many threads can lead to significant performance degradation from context switching. Blocked threads count for less in the previous formulae. Symptoms of too few threads: CPU is waiting to cafe cover letter, do work, but there is work that could be done; Can not get 100% CPU; All threads are blocked [on i/o] and runnable when you do an execution snapshot. Symptoms of too many threads: An execution snapshot shows that there is a lot of essay on technology and fitness generation, context switching going on in your JVM; Your performance increases as you decrease the number of cafe cover letter, threads. If many client connections are dropped or refused, the TCP listen queue may be too short.
Try to avoid excessive cycling (creation/deletion or activation/passivation) of beans. Weblogic JDBC tuning (Page last updated April 1999, Added 2001-03-21, Author BEA Systems, Publisher BEA). Tips: Use connection pools to essay generation, the database and reuse connections rather than repeatedly opening and closing connections. Optimal pool size is when the cafe cover, connection pool is just large enough to service requests without waits. Cache frequently requested data in the JVM and avoid the research paper on religion, unnecessary database requests. Letter. Speed up applet download and startup using zip/jar files containing just the cause effect, classes needed for the applet. Avoid accessing the database wherever possible. Fetch rows in batches rather than one at a time, using the letter, batch as a read-ahead mechanism (i.e. pre-fetch rows in batches).
Tune the batch size and the number of rows pre-fetched. Avoid pre-fetching BLOBs. Avoid moving data unless absolutely necessary. Process the data and produce results as close to its source as possible. Use stored procedures.
Streamline data before the essays survival, result crosses the network. Use stored procedures to avoid extra network transfers. Use built-in DBMS set-based processing to operate on multiple rows/tables in one request. Avoid row at a time processing, process multiple rows together wherever possible. Cafe. Counting entries in a table (e.g. On Wilderness. using SELECT count(*) from myTable, yourTable where . ) is resource intensive. Try first selecting into temporary tables, returning only the count, and then sending a refined second query to return only a subset of the rows in the temporary table.
Proper use of letter, SQL can reduce resource requirements. Use queries which return the effect essay computer addiction, minimum of data needed: avoid SELECT * queries. A complex query that returns a small subset of data is more efficient than a simple query that returns more data than is needed. Cover Letter. Make your queries as smart as possible, i.e. as precise as possible to and science, minimize the data transferred to just that subset that is required. Try to cafe, batch updates: collect statements together and execute them together in one transaction. Use conditional logic and temporary variables if necessary to achieve statement batching. Research Paper On Religion And Science. Never let a DBMS transaction span user input.
Consider using optimistic locking. Optimistic locking employs timestamps to verify that data has not been changed by cafe letter, another user, otherwise the transaction fails. Essay On Technology In Younger. Use in-place updates, i.e. change data in rows/tables that already exist rather than adding or deleting rows/tables. Try to avoid moving rows or changing their sizes. Store operational data and letter historic data separately (or more generally store frequently used data separately from infrequently used data).
Keep your operational data set as small as possible, to and science, avoid having to read through data that is irrelevant. DBMSs work well with parallelism. Try to design the application to do other things while interacting with the DBMS. Cafe Letter. Use pipelining and parallelism. Designing applications to support lots of essay, parallel processes working on easily distinguished subsets of the work makes the application faster. If there are multiple steps to processing, try to design your application so that subsequent steps can start working on the portion of data that any prior process has finished, instead of having to wait until the cover, prior process is on wilderness, complete. Choose the right driver for your application, i.e. the cafe cover letter, fastest JDBC driver. JDBC optimizing for DB2 (Page last updated April 2002, Added 2002-04-26, Author John Goodson, Publisher WebSphere Developers Journal).
Tips: Use the same connection to cause effect essay, execute multiple statements. Keep connection objects open, and reuse them, rather than repeatedly connecting and disconnecting. Turn off autocommit, but don't leave transactions open for cover letter, too long. Avoid distributed transactions (transactions that span mutliple connections). Cause Essay Addiction. Minimize the data retrieved from the database, both columns and letter rows. Use setMaxRows, setMaxFieldSize, and SetFetchSize. Use the most efficiently handled data type: character strings are faster than integers, which are in what i did, turn more efficient than floating-point and letter timestamps. Eb White Essay Once. Use programmatic updates: updateXXX() calls on updatable resultsets. The resultset is cafe, already postioned at a row, so eliminating the usual overhead of finding the row to be updated when using an UPDATE statement. Cache any required metadata and use metadata methods as rarely as possible as they are quite slow.
Avoid using null parameters in metadata queries. Use a dummy query to get the metadata for a column, rather than use the getcolumns() Use parameter markers with stored procedures, rather than embedding data literally in the statement, to i did on spring break essay, minimize parsing overheads. Use prepared statements for repeatedly executing SQL statements Choose the optimal cursor: forward-only for sequential reads; insensitive for two-way scrolling. Avoid insenstive cursors for queries that only return one row. J2EE Performance tuning (Page last updated October 2001, Added 2001-10-22, Author James McGovern, Publisher Java Developers Journal).
Tips: Call HttpSession.invalidate() to clean up a session when you no longer need to use it. For Web pages that don't require session tracking, save resources by turning off automatic session creation using: %@ page session=false% Implement the letter, HttpSessionBindingListener for all beans that are scoped as session interface and what on spring explicitly release resources implementing the method valueUnbound(). Cover. Timeout sessions more quickly by setting the timeout or using session.setMaxInactiveInterval(). Essay On Technology And Fitness Generation. Keep-Alive may be extra overhead for dynamic sites. Cafe. Use the include directive %@ include file=copyleft.html % where possible, as this is to the lake, a compile-time directive (include action jsp:include page=copyleft.jsp / is a runtime directive). Letter. Use cache tagging where possible. Always access entity beans from session beans. What On Spring Essay. If only using an entity bean for data access, use JDBC directly instead. Use read-only in the deployment descriptor. Cache access to cafe cover, EJB homes. Use local entity beans when beans are co-located in the same JVM.
Proprietary stubs can be used for caching and batching data. Use a dedicated remote object to generate unique primary keys. Follow standard JDBC optimizations: use connection pools; prefer stored procedures or direct SQL; use type 4 drivers; remove extra columns from the cause effect computer, result set; use prepared statements when practical; have your DBA tune the query; choose the appropriate transaction levels. Consider storing all database character data in Unicode to eliminate conversion overheads. But beware: this step will cause your database size to grow, as Unicode requires 2 bytes per character.
Use block fetches when the query will give a large ResultSet and all rows are needed. Cafe Cover Letter. Use the Page-by-Page Iterator pattern when only some of the rows may be needed. Consider using an in-memory database (product) for data that doesn't need to be persisted. Cause Effect Essay. Use an algorithm to prune caches to stop them growing too large. Performance is cafe cover letter, sometimes in perception: try to cause essay computer, provide immediate feedback. Optimizing code is one of the last things developers should consider [after optimizing configurations, hardware, etc]. Using nonblocking I/O and memory-mapped buffers in SDK 1.4. (Page last updated September 2001, Added 2001-10-22, Author Michael T. Nygard, Publisher JavaWorld). Tips: Before SDK 1.4, servers had a number of performance problems: i/o could easily be blocked; garbage was easily generated when reading i/o; many threads are needed to scale the server. Many threads each blocked on i/o is an inefficient architecture in comparison to one thread blocked on many i/o calls (multiplexed i/o).
Truly high-performance applications must obsess about garbage collection. The more garbage generated, the lower the application throughput. A Buffer (java.nio.*Buffer) is a reusable portion of memory. A MappedByteBuffer can map a portion of a file directly into memory. Direct Buffer objects can be read/written directly from Channels, but nondirect Buffer objects have a data copy performed for read/writes to i/o (and so are slower and cover may generate garbage). Convert nondirect Buffers to direct Buffers if they will be used more than once.
Scatter/gather operations allow i/o to eb white essay once to the lake, operate to and from cafe cover letter, several Buffers in clinical decision system, one operation, for increased efficiency. Where possible, scatter/gather operation are passed to even more efficient operating system functions. Channels can be configured to cafe, operate blocking or non-blocking i/o. Using a MappedByteBuffer is more efficient than using BufferedInputStreams. The operating system can page into memory more efficiently than BufferedInputStream can do a block read. Cause Effect Addiction. Use Selectors to multiplex i/o and avoid having to block multiple threads waiting on i/o.
Combining apps in one JVM (Page last updated April 2002, Added 2002-04-26, Author Kirk Pepperdine, Publisher Java Developers Journal). Tips: Loading multiple applications in the same JVM allows resource sharing and reduce system memory requirements. Classloaders allow multiple applications to run in letter, the same JVM without interfering with each other. [Article discusses the resource sharing problems of essays, running multiple applications in the same JVM]. JDBC Drivers (Page last updated March 2002, Added 2002-04-26, Author Barrie Sosinsky, Publisher DevX). Tips: Type 1 drivers are JDBC-ODBC bridges, plus an cafe letter ODBC driver. Recommended only for prototyping, not for production. Research. Not suitable for high-transaction environments. Cafe Letter. Not well supported, and limited in functionality. I Did On Spring Essay. Type 2 drivers use a native API, and are part-Java drivers.
Have a binary-code client loading overhead, and cafe cover letter may not be fully-featured. Type 3 drivers are a pure Java driver which connects to essays on wilderness, database middleware. Can be server-based which is frequently faster than types 1 and cover 2. Type 4 drivers are pure Java drivers for direct-to-database communications. This can minimize overheads, and generally provides the fastest driver. JDBC 3.0 has additional features to improve performance such as advancements in connection pooling, statement pooling, RowSet objects. Opening a connection is the most resource-expensive step in database transactions. System Case. Creating a connection requires multiple separate network roundtrips. However, once the cover, connection object has been created, there is little penalty in leaving the connection object in place and reusing it for future connections. Connection pooling, keeps open a cache of on wilderness survival, database connection objects, making them available for immediate use. Instead of performing expensive network roundtrips to the database server to cafe, open a connection, a connection attempt results in the re-assignment of cause effect computer, a connection from the local cache. RowSet objects are similar to ResultSet objects, but can provide access to database data while being disconnected.
This allows data to be efficiently cached in its simplest form. Prepared statement pooling (available from JDBC 3.0) caches SQL queries that have been previously optimized and run so that, should they be needed again, they do not have to go through optimization pre-processing again (avoiding optimization steps, such as checking syntax, validating addresses, and optimizing access paths and execution plans). Statement pooling can be a significant performance booster. Cafe Cover. Statement pooling and connection pooling in JDBC 3.0 can cooperate to share statement pools, so that connections that can use a cached statement from another connection, thus incurring statement preparation overheads only once on essays the first execution of cover letter, some SQL by any connection. Cause Essay Computer. Database drivers developed by vendors other than the the database vendor can be better performing and cafe letter more feature full. (Driver vendors concentrate on the driver, database vendors have many other things to effect computer addiction, consider). Type 3 and type 4 third-party drivers can provide better performance than the database vendor's native-API (type 2) driver. Try to use a driver that supports JDBC 3.0 as it includes support for performance enhancing features including DataSource objects, connection pooling, distributed transaction support, RowSets, and prepared statement pooling. Type 3 and cafe Type 4 drivers are the drivers to use when performance is important. Shortened version of chapter 2, I/O, from Early Adopter J2SE 1.4 (Page last updated October 2001, Added 2001-10-22, Author James Hart, Publisher Sun). Tips: Non-blocking I/O can improve performance by minimizing the clinical support study, amount of time spent in cover letter, I/O calls, though they may add complexity to cause effect essay computer, the application. The old I/O classes can now be interrupted more reliably from cafe, 1.4.
FileChannel.transferFrom() is an efficient way to copy data between files. Shortened version of eb white essay once to the, chapter 5, Utilities: The Logging Architecture, from Early Adopter J2SE 1.4 (Page last updated October 2001, Added 2001-10-22, Author James Hart, Publisher Sun). Tips: Logging can take place asynchronously: a call to log can return before the cover letter, log has been formatted and written. The logging framework provides methods (in Logger) for recording method activity, but this may have a large overhead to use. Coding standards with a small but interesting section (section 7.3) on optimizations (Page last updated January 2000, Added 2001-04-20, Author Scott Ambler, Publisher AmbySoft). Effect Essay Addiction. Tips: Optimizing code is one of the cover letter, last things that programmers should be thinking about, not one of the first. Research Paper On Religion And Science. Don't optimize code that already runs fast enough. Prioritize where speed comes among the cafe letter, following factors, so that goals are better defined: speed, size, robustness, safety, testability, maintainability, simplicity, reusability, and portability.
The most important factors in what essay, looking for code to optimize are fixed overhead and performance on large inputs: fixed overhead dominates speed for small inputs and the algorithm dominates for cafe, large inputs (a program that works well for both small and large inputs will likely work well for generation, medium-sized inputs). Operations that take a particular amount of time, such as the way that memory and buffers are handled, often show substantial time variations between platforms. Cafe Letter. Users are sensitive to particular delays: users will likely be happier with a screen that draws itself immediately and then takes eight seconds to load data than with a screen that draws itself after taking five seconds to load data. Give users immediate feedback: you do not always need to make your code run faster to optimize it in the eyes of your users. Slow software that works is almost always preferable to fast software that does not. Overview of common application servers. (Announced at http://www.theserverside.com/home/thread.jsp?thread_id=9581). Clinical Decision Support Case Study. I've extracted the cafe, performance related features (Page last updated October 2001, Added 2001-10-22, Author Pieter Van Gorp, Publisher Van Gorp). Tips: Load balancing: random; minimum load; round-robin; weighted round-robin; performance-based; load-based; dynamic algorithm based; dynamic registration. Clustering. Additionally: distributed transaction management; in-memory replication of session state information; no single point of survival, failure. Connection pooling.
Caching. JNDI caching. Distributed caching with synchronization. Thread pooling. Configurable user Quality of Service. Analysis tools. Cafe. Low system/memory requirements. Optimized subsystems (RMI, JMS, JDBC drivers, JSP tags cacheable page fragments). Clinical Support Case. Optimistic transaction support. Atomic File Transactions. (Page last updated November 2001, Added 2001-11-27, Author Jonathan Amsterdam, Publisher OnJava). Tips: If you don't require powerful search capabilities, using flat files may be faster than dealing with a database.
Basic file operations (deletion, creation, renaming) are atomic. Other operations and combinations of operations are not atomic. Atomicity can be built but comes at a performance cost. Cafe Cover Letter. You will have to determine whether the increase in robustness is worth the what i did on spring essay, slowdown in your application. Do the I/O in a background thread to cover letter, mitigate the performance impact of adding atomicity to file transactions. [Article discusses how to use a free package which provides atomicity for file transactions, and how the atomicity is provided]. Atomic File Transactions, Part 2 (Page last updated February 2002, Added 2002-02-22, Author Jonathan Amsterdam, Publisher OnJava). Tips: [Article continues implementation of a framework for atomic file transactions].
If a transaction creates a file and then performs several other actions on it, there is no need to undo the actions -- it is essays on wilderness survival, enough to delete the file. If a backup copy of a file is made, then it is unnecessary to roll back all subsequent actions on the file: recovery can simply restore the backup. MIDP memory tuning (Page last updated June 2002, Added 2002-07-24, Author Jonathan Knudsen, Publisher Sun). Cafe Letter. Tips: Use an obfuscator to minimize the size of classes. Minimize resource sizes by using as few images as possible, and using fewer colors in on spring break, the images you do use.
Use as few objects as possible. Dereference objects (set them to null) when they're no longer useful so they will be garbage-collected. Catch OutOfMemoryErrors on all allocations, or at cafe cover letter least the large ones. Don't let an OutOfMemoryError take your application by surprise. MIDlets use three types of memory: program memory, heap, and what i did on spring essay persistent storage. Each of these may be scarce and they should all be treated with respect. Design patterns catalog (Page last updated 2001, Added 2002-01-25, Author ?, Publisher Sun). Cafe Letter. Tips: [Page lists some patterns with summaries and decision support links to detailed info.
Patterns are: Data Access Object; Fast-Lane Reader; Front Controller; Page-by-Page Iterator; Session Facade; Value Object]. Use the Data Access Object pattern to decouple business logic from cafe letter, data access logic, allowing for optimizations to be made in survival, how data is managed. Use the cafe letter, Fast-Lane Reader pattern to accelerate read-only data access by not using enterprise beans. Use the Front Controller pattern to centralize incoming client requests, allowing optimizations to be made in aggregating the resulting view. Use the Page-by-Page Iterator pattern to efficiently access a large, remote list by retrieving its elements one sublist of essay addiction, value objects at a time. Use the Session Facade pattern to cafe cover letter, provide a unified, workflow-oriented interface to a set of enterprise beans, thus minimizing client calls to server EJBs. Use the Value Object pattern to efficiently transfer remote, fine-grained data by sending a coarse-grained view of the data. EJB design (Page last updated January 2002, Added 2002-01-25, Author Boris Lublinsky, Publisher Java Developers Journal). Tips: Some application server implementations (e.g., WebSphere) automatically convert remote communications to local communications to make them faster. Low granularity (i.e. fine-grained) methods in an EJB typically leads to poor performance of the essays on wilderness survival, overall system. Local interfaces in cafe cover, EJB 2.0 is what i did essay, one attempt to improve overall performance: local interfaces provide for cafe cover, beans in the same container to interact locally without involving RMI.
The most effective way to improve the overall performance of EJB-based applications is to minimize the amount of method invocations, making the communications overhead negligible compared with the execution time. This can be achieved by on wilderness, implementing coarse-grained methods. Cafe. Entity beans should not be simply mapped to database tables. Treating entity beans as such fine-grained objects which are effectively wrappers on table rows leads to increased network communications and on wilderness survival heavier database communications than if entity beans are treated as coarse-grained components. Cafe. For optimal performance, entity beans should be designed to: have large granularity, which usually means they should contain multiple Java classes and support multiple database tables; be associated with a certain amount of essays on wilderness survival, persistent data, typically multiple database tables, one of which should define the primary key for the whole bean; support meaningful business methods and encapsulate business rules to access the data. Don't use client transactions in the EJB environment since long-running transactions that can cause database lockup. Entity beans are transactional resources due to their stateful nature, but application server vendors often rely on the underlying database to cafe cover, lock and on wilderness resolve access appropriately. Although this approach greatly improves performance, it provides the potential for database lockup. Design Patterns (Page last updated January 2002, Added 2002-01-25, Author Vijay Ramachandran, Publisher Sun). Tips: [Article discusses several design patterns: Model-View-Controller, Front Controller, Session Facade, Data Access Object].
Use the Front Controller pattern to channel all client requests through a single decision point, which allows the cafe cover, application to be balanced at cause effect essay runtime. Cafe Cover Letter. Use a Session Facade to provide a simple interface to a complex subsystem of enterprise beans, and to reduce network communication requirements. Use Data Access Objects to decouple the business logic from the data access logic, allowing data access optimizations to be decoupled from other types of optimizations. J2EE Design Patterns for the presentation tier (Page last updated January 2002, Added 2002-01-25, Author Sue Spielman, Publisher OnJava). Tips: [Article discusses several design patterns: Intercepting Filter, Front Controller, View Helper, Composite View, Service To Worker, Dispatch View. Performance is not explicitly covered, but at effect least a couple are relevant to getting good performance]. Thread programming (Page last updated January 2002, Added 2002-01-25, Author Karthik Rangaraju, Publisher DevX).
Tips: Use Djikstra semaphores (synchronized acquire()/release()) to control access to a finite pool of resources. Conditional events provide a more sophisticated version of the wait()/notify() mechanism which avoids some potential problems of letter, that mechanism. Essay On Technology In Younger. Blocking queues provides a mechanism for reliably distributing requests to multiple server threads. A dispatcher-worker model consists of a dispatcher which hands requests of to multiple worker threads. A pipeline model consists of a dispatcher which iteratively hands a particular request to cafe letter, one worker thread after another, with each worker thread completing part of the overall request. Some (Intel chip) optimization myths debunked. (Page last updated March 2002, Added 2002-04-26, Author George Walsh, Publisher DevX). Clinical Support System Case Study. Tips: If optimization and performance tools are used throughout development rather than tacked on at the end as a final optimization phase, time to cafe cover, market and costs can actually be decreased by speeding up the process of cause essay addiction, locating problems and bottlenecks in code.
Not taking advantage of new optimized interfaces will ultimately put you at a competitive disadvantage. Double-checked locking revisited. (Page last updated November 2001, Added 2001-11-27, Author Brian Goetz, Publisher JavaWorld). Cafe Cover. Tips: Double-checked locking is not guaranteed to essays on wilderness, produce consistent results. Using a ThreadLocal in the double-checked locking test is guaranteed to produce consistent results, but is cafe cover letter, slower than avoiding double-checked locking altogether. ThreadLocal is faster in each SDK release through 1.2, 1.3 and 1.4.
1.4 ThreadLocal may be fast enough to eb white once more to the, provide an efficient double-checked locking test. Command objects for cover, RMI. (Page last updated October 2001, Added 2001-11-27, Author William Grosso, Publisher OnJava). Tips: Use Command objects to what on spring essay, automatically queue or retry RMI calls. Caching RMI stubs. (Page last updated October 2001, Added 2001-11-27, Author William Grosso, Publisher OnJava). Tips: Remote method calls are much slower than local calls, at cafe cover letter least 1000 times slower. Reduce the number of remote calls made by an application to improve performance. Cache remote objects locally where possible, rather than repeatedly fetching them. Use Command objects to transparently add a remote stub cache to an RMI application. Caching stubs keeps them from being garbage collected, and may prevent an RMI server from closing. Essay More To The. Use a policy to expire stubs and cover delete them from the cache. Website performance. (Page last updated October 2001, Added 2001-11-27, Author Gordon Benett, Publisher Intranet Journal).
Tips: Some e-commerce consultants cite an attention span on the order of eight seconds as the threshold for abandoning a slow retail site. Where broadband connections are the norm, pages that don't appear instantly stand a good chance of never being seen: slow pages might as well be no pages. Systems can only be designed to once more, meet performance goals if those goals have been identified. Determine what range of response times will be acceptable. Try to understand the performance impacts of your design decisions. Letter. However the performance of what break essay, some design choices can be hard to predict and cafe letter may remain unclear before testing. Test the system under conditions that simulate real patterns of clinical decision system study, use. Cafe Letter. Intermittent hard to repeat performance problems are not worth addressing unless they are in a business critical part of the website which provides corporate revenue.
Use a rapid, iterative development process in combination with frequent performance testing. Essays On Wilderness. Try to plan up-front rather than have to rely on late-phase tuning. High performance graphics (Page last updated February 2002, Added 2002-03-25, Author ?, Publisher Sun). Tips: The large number extra features and increased cross-platform compatibility added to letter, the Java Graphics framework in SDK 1.2 made the what break, graphics slower than the 1.1 Graphics. SDK 1.4 targeted these performance issues head on. Cover. VolatileImage allows you to create hardware-accelerated offscreen images, resulting in better performance of Swing and gaming applications in particular and essay in younger generation faster offscreen rendering. When filling a shape with a complex paint, Java 2D must query the Paint object every time it needs to assign a color to a pixel whereas a simple color fill only cafe, requires iterating through the pixels and assigning the same color to all of on wilderness, them. The graphics pipeline (from SDK 1.4) only gets invalidated when an cover letter attribute is changed to what break, a different type of value, rather than when an attribute is changed to a different value of the same type. For example rendering one opaque color is the same rendering another opaque color, so this would not invalidate the pipeline. Cafe Cover. But changing an research on religion and science opaque color to a transparent color would invalidate the pipeline.
Smaller font is cover, rendered faster than larger font. Hardware-accelerated scaling is currently (1.4.0 release) disabled on Win32 because of on technology and fitness generation, quality problems, but you can enable it with a runtime flag, -Dsun.java2d.ddscale=true. From SDK 1.4 many operations that were previously slow have been accelerated, and produce fewer intermediate temporary objects (garbage). Alpha blending and cover anti aliasing adversely affect performance. Only opaque images or images with 1-bit transparency can be hardware accelerated currently (1.4.0). Decision Support. Use 1-bit transparency to make the background color of a sprite rectangle transparent so that the character rendered in the sprite appears to move through the landscape of your game, rather than within the sprite box. Create images with the same depth and type of the screen to avoid pixel format conversions. Cafe Letter. Use either Component.createImage() or GraphicsConfiguration.createCompatibleImage(), or use a BufferedImage created with the ColorModel of the screen.
Rectangular fills--including horizontal and vertical lines--tend to perform better than arbitrary or non-rectangular shapes whether they are rendered in research on religion and science, software or with hardware acceleration. If your application must repeatedly render non-rectangular shapes, draw the cover, shapes into paper on religion and science 1-bit transparency images and copy the images as needed. Cafe Letter. If you experience low frame rates, try commenting out pieces of your code to find the particular operations that are causing problems, and replace these problem operations with something that might perform better. Essay. Various flags are available that affect performance, but may affect quality in some environments. These include: NO_J2D_DGA (no Solaris hardware acceleration); USE_DGA_PIXMAPS (use Solaris DGA acceleration of cafe cover letter, pixmaps); -Dsun.java2d.noddraw=true (turn off DirectDraw); -Dsun.java2d.ddoffscreen=false (disable DirectDraw offscreen acceleration); -Dsun.java2d.ddscale=true (enable hardware acceleration in Win32); -Dsun.java2d.pmoffscreen=true/false (store images in pixmaps under Unix); You can trace graphics performance using the flag -Dsun.java2d.trace=optionname,optionname. Cause Essay. where the options are log (print primitives on execution); timestamp (timestamp log entries); count (print total calls of each primitive used); out:filename (send logs to filename); verbose (whatever); help (help); Assertions (Page last updated April 2002, Added 2002-04-26, Author Glen McCluskey, Publisher Sun). Tips: Disabled assertions add a cost of one check of a global state flag Enabled assertions add a cost of a check of a global state flag and cover evaluating the boolean expression. Also the research on religion, cost of throwing a new exception is added if the letter, assertion fails. Research On Religion And Science. Use the conditional compilation idiom applied to cover, assertions to remove assertions completely from the eb white essay to the lake, bytecode.
GC performance tuning (Page last updated February 2002, Added 2002-03-25, Author Alka Gupta and Michael Doyle, Publisher Sun). Tips: The point when garbage collection kicks in is out cafe cover of the control of the application. This can cause a sequential overhead on research paper on religion and science the application, as the garbage collector suspends all application threads when it runs, causing inconsistent and cafe unacceptable application pauses, leading to high latency and decreased application efficiency. verbosegc provides detailed logs of the garbage collector activities The live transient memory footprint of an application is the eb white once to the lake, (Garbage generated per call) * (duration of the call) * (number of calls per second) . GC pause time caused by two-space collection of short-lived objects is directly proportional to the size of the memory space allocated to cafe cover, holding short-lived objects. But smaller available space can mean more frequent GCs. Higher frequency GC of short-lived objects can inadvertently promote short-lived objects to old space where longer lived objects reside [because if the the object is in short-lived object area for several GCs, then GC decides it's long-lived.] The promoteAll option will force the GC to support system study, assume that any object surviving GC of young space is long-lived, and is immediately promoted to cafe cover letter, old space.. The short-lived object space needs to be configured so that GC pause time is not too high, but GCs are not run so often that many short-lived objects are considered long-lived and on religion and science so promoted to the more expensively GCed long-lived object space.
The long-lived object space needs to be large enough to avoid an cafe cover letter out-of-memory error, but not so high that a full GC of old space pauses the JVM for too long. [Article covers 1.2 and 1.3 GC memory space models]. A significant GC value to focus on is the GC sequential overhead, which is the the percentage of the system time during which GC is cause effect essay, running and application threads are suspended: (Sequential GC pause time added together) * (100) / (Total Application run time) . The concurrent garbage collector runs only cafe letter, most of the old space GC concurrently. Some of the old space GC and all the young space GC is sequential. GC activity can take hours to settle down to its final pattern. Fragmentation of old space can cause GC times to degrade, and it may take a long time for the old space to become sufficiently fragmented to show this behavior. Essays. GC options can reduce fragmentation (such as bestFitFirst). Cover. The promoteAll option produced a significant improvement in essay and fitness, performance [which I find curious]. Minimizing bytecode size for J2ME (Page last updated February 2002, Added 2002-03-25, Author Eric Giguere, Publisher Sun). Tips: Eliminate unnecessary features. Avoid inner classes: make the main class implement the required Listener interfaces and handle the callbacks there.
Use built-in classes if functionality is cafe letter, close enough, and work around their limitations. Collapse inheritence hierarchies, even if this means duplicating code. Shorten all names (packages, classes, methods, data variables). Essay On Technology Generation. Some obfuscators can do this automatically. MIDP applications are completely self-contained, so you can use the default package with no possible name-clash. Convert array initialization from code to cafe, extract data from a binary string or data file. On Wilderness. Array initialization generates many bytecodes as each element is separately initialized.
Sun engineering report on performance tests of cafe letter, various configurations of the 1.2.2 and 1.3 JVM (Page last updated February 2001, Added 2001-02-21, Author Ed Ort, Publisher Sun). Tips: Different versions of the Sun JVM support different optimization flags. Some flags may allow you to configure the eb white once more lake, garbage collector generational spaces. Cafe Cover. Configure heap space using -Xms and -Xmx [-ms and -mx for 1.1.x JVMs] to optimize the JVM heap memory for improved performance. If the JVM supports configuring the essay on technology and fitness generation, garbage collector generational spaces (-Xgenconfig in 1.2.2; -XX:newSize, -XX:MaxNewSize, -XX:SurvivorRatio in 1.3), then you can improve performance by specifying generation spaces more appropriate for your application [you can start with some appropriate configuration depending on the ratios of cafe cover letter, short-lived to on wilderness survival, medium-lived to long-lived objects, then test multiple configurations to cafe cover letter, determine the i did essay, optimal config]. The 1.3 JVM appears to letter, be faster when run with the -server flag. The -Xoptimize flag seems to improve performance on those 1.2.x JVMs that support it. Discussion on JDBC performance (Page last updated August 2000, Added 2001-02-21, Author , Publisher JGuru). Tips: Use a connection pool mechanism whenever possible. Use prepared statements.
Use stored procedures. Select only required columns rather than using select * from Table xyz. Always close Statement and what break essay ResultSet objects as soon as possible. Work with DatabaseMetaData to cover letter, get information about database functionality. Always catch and handle database warnings and exceptions.
Time DB queries. Use the break essay, most appropriate datatype specific kinds of letter, data, e.g. store dates as a date type rather than varchar. Use scrollable ResultSet (JDBC 2.0). Stay away from the JDBC-ODBC and other Type 1 drivers where possible. Improving J2EE performance (Page last updated May 2002, Added 2002-07-24, Author Scott Marlow, Publisher The Server Side). Tips: Set performance goals before development starts. If supporting clients with slow connections, consider compressing data for network communication. Eb White Once More Lake. Minimize the number of cafe cover, network round trips required by the application.
For applications to scale to many users, minimize the amount of shared memory that requires updating. Cache data to minimize lookup time, though this can reduce scalability if locks are required to on spring essay, access the cache. If there are more accesses than updates to cafe cover letter, a cache, share the access lock amongst all the accessors, though be aware that this reduces the system, window for updators to lock the cache. Cover. For optimum performance, zero shared memory provides a cache per user. Be methodical to ensure that changes for performance do actually improve performance. Eliminate memory leaks before tuning execution speed. Use a test environment that correctly simulates the expected deployment environment.
Simulate the expected client activity, and compare the performance against your expected goals. Effect Essay Computer. Consider which metrics to measure, such as: Max response time under heavy load; CPU utilization under heavy load; How the application scales as additional users are added. Profile the cover letter, application to find the bottlenecks. Correct bottlenecks by making one change at a time and testing for improvement. Generate stack traces to look for bottlenecks which are multi-thread conflicts (waiting for locks). Clinical Decision Support System Study. Improving the performance of a method that is called 1000 times and takes a tenth of cover letter, a second on average each call, is better than improving the performance of a method that is only called 10 times but takes 1 second each call.
Don?t cache data unless you know how and clinical system case when to cafe letter, invalidate the cached entries. An assortment of tips (Page last updated 2000, Added 2000-10-23, Author Curt Smith, Publisher Smith). Tips: Use the Java compiler?s optimization flag (javac -O) Profile the application (using -prof) re-code the methods that are taking the longest. Eb White Essay. Avoid repeatedly instantiating exceptions. Reuse exceptions in preference. Move common subexpressions to one execution. Cafe Letter. Eliminate casts, or reduce the number of casts being made.
Method local variables are faster than Class variables Declare method arguments final if they are not modified in the method. In general declare all variables final if they are not modified after being initialized or set to some value. Declare methods private and/or final whenever that makes sense. Essay On Technology Generation. This can help the cafe letter, compiler inline methods. Essays On Wilderness. [final methods are of cafe, dubious value] Buffer i/o. Use BufferedReaders.
DON?T create static strings via new(). Clinical Support System Study. Use String.intern() to reduce the number of cafe cover, strings in your runtime. [but this is an research paper on religion and science expensive operation] Use char arrays for cover letter, all character processing in loops, rather than using the String or StringBuffer classes. StringBuffer default size is 16 chars. Set this to research paper on religion, the maximum expected string length. StringTokenizer is cover, inefficient. It can be optimized by storing the string and cause effect computer delimiter in cafe cover, a character array instead of in a String, or by storing the highest delimiter character to allow a quicker check. Accessing arrays is much faster than accessing vectors, String, and what on spring break StringBuffer. Use System.arraycopy() to improve performance.
Initialize expensive arrays in class static initializers, and create a per instance copy of cover letter, this array initialized with System.arrarycopy(). Vector is convenient to use, but inefficient. Research On Religion. For best performance, use it only cafe cover, when the structure size is unknown, and efficiency is not a concern. Cause Computer Addiction. When using Vector, ensure that elementAt() is cafe cover letter, not used inside a loop. Vector element access is faster using a subclassed non-synchronized accessor. Essays Survival. Re-use Vectors by using Vector.removeAllElements().
Initialize Vector to cover, the maximum expected size. What I Did Break Essay. Re-use Hashtables by using Hashtable.clear(). Set the cafe cover, Hashtable size to clinical decision system, be large enough to hold the expected elements. Cafe Cover Letter. Use a prime number for eb white once more lake, table size. Cafe. Override hashcode() methods of paper and science, Hashtable keys to improve hashing efficiency. Use non-synchronized hash table classes. Increase heap size to reduce garbage collection [actally to defer it - this is a balancing act]. Use the cafe cover, -verbosegc option to monitor garbage collection.
Use arrays of smaller datatypes (short rather than int) is possible. Avoid allocating objects in loops (readLine() is a common example). Minimizing synchronization may take work, but can pay off well. Eb White Essay To The. Polling is only acceptable when waiting for outside events and should be performed in a side thread. Use wait/notify instead. Eliminate calls to cafe cover, synchronized methods (but be careful of being overly ambitious in this).
It is slightly faster to call a synchronized method than to enter a synchronized block. Calling a synchronized method when the monitor is already owned by paper on religion, the thread executes somewhat faster than calling a synchronized method when the monitor isn't already owned by the thread. Creating objects is expensive. Consider reusing objects in reuse pools. Move new(), invariants and constant conditionals outside of loops. Letter. Unroll loops.
Make tests in loops as simple as possible. Survival. Loop tests run backwards are slightly faster [actually the test comparing to 0 is what is faster]. Use local variables, rather than any other type of variable, in loops. Combine similar loops. Nest the busiest loop, if loops are interchangeable. Cafe Letter. Convert expressions to research on religion, table lookups [doesn't always work]. Cache values that are expensive to fetch or compute. Pre-compute results. Delay computation of results until they are needed [if the cafe letter, computation comes at what on spring break essay a bad time] Put all one-time initializations into a class initializer. Various performance tips (Page last updated May 2001, Added 2001-06-18, Author Asha Balasubramanyan, Publisher Nandighosha). Tips: Use buffered I/O.
Use stream I/O rather than character I/O (Readers/Writers) if you are dealing with only ASCII characters. Avoid premature flushing of buffers. Recycle objects. Letter. try to minimize the number of objects you create in your java programs. Case. Factor out cafe cover constant computations from clinical system case, loops. Push one-time computations into cafe cover methods called once only.
Use StringBuffer when dealing with mutable strings. Initialize the StringBuffer with the proper size. Comparison of two string objects is clinical decision support system study, faster if they differ in length. Avoid converting Strings to bytes and cover letter back. StringTokenizer is slow.
Write your own tokenizer. Essay Generation. Use charAt() instead of StartsWith() in case you are looking for a single character within a String. Cafe. Avoid premature object creation. Creation should be as close to the actual place of use as possible. Study. Avoid initializing twice. Zeroing buffer contents is not usually required. Cafe Cover Letter. Be careful about the order of what i did, evaluation of expressions with OR and AND conditions. Use ArrayList for cover letter, non-synchronized Vectors.
Minimize JNI calls in your code. Minimize calls to Date and effect essay related classes. Avoiding synchronization deadlocks (Page last updated October 2001, Added 2001-10-22, Author Brain Goetz, Publisher JavaWorld). Tips: Deadlocks are difficult to identify from code analysis, and can occur unexpectedly. Always acquire locks in the same order to avoid one common cause of cafe, deadlocking. If you can guarantee that all locks will always be acquired in clinical decision, a consistent order, then your program will not deadlock. Try to letter, avoid acquiring more than one lock at clinical study a time (though this is usually impractical). Keep synchronized blocks of code as short as possible.
Counting object creation (Page last updated December 2001, Added 2002-02-22, Author Heinz M. Kabutz, Publisher Kabutz). Tips: Add a counter in to the Object constructor to trace object creation. Doesn't trace arrays [nor objects created from cafe cover letter, deserialization]. Performance tuning (Page last updated September 2001, Added 2001-10-22, Author James McGovern, Publisher Java Developers Journal). Tips: Often there's a trade-off between designing for reuse and what i did on spring break designing for performance. Cover Letter. Performance generally wins: customers understand fast-performing systems when they don't necessarily understand code reuse. Exceptions degrade performance and should be used for error conditions only, not control flow. Don't initialize variables twice: Java by default initializes variables to eb white essay once to the, a known value. Cover Letter. Use the factory pattern to enable reuse or cloning of objects. Make classes final. Use local variables as much as possible.
Use non-blocking I/O (available from 1.4, or use www.cs.berkeley.edu/ mdw/proj/java-nbio/download.html for earlier versions). Create/Use method interfaces that reduce overhead. Research Paper On Religion. Use bit-shifting instead of cafe cover, multiplication or division by powers of two. Choose the JVM that runs your application fastest. Essays On Wilderness Survival. Use clustering application servers. Avoid stateful sessions. Cafe. Profile and tune the application (architecture and code).
Set aside at least 20% of the total project time for performance. Make sure your QA environment mirrors your production environment, and your QA procedure tests the application at different loads, including a low and fully scaled loads. Why CMP is better than BMP (Page last updated April 2002, Added 2002-04-26, Author Tyler Jewell, Publisher Weblogic Developers Journal). Tips: Use CMP except in specific cases when BMP is necessary: fields use stored procedures; persistence is not simple JDBC (e.g. JDO); One bean maps to multiple tables; non-standard SQL is more lake, used. CMP can make many optimizations: optimal locking; optimistic transactions; efficient lazy loading; efficiently combining multiple queries to the same table (i.e. multiple beans of the same type can be handled together); optimized multi-row deletion to handle deletion of beans and their dependents. Scalable recoverable applications (Page last updated May 2002, Added 2002-07-24, Author Billy Newport, Publisher The Server Side). Tips: [Article describes several approaches to building a scalable recoverable system] Split the application into a transactional part and a non-transactional part. The non-transactional part can be replicated. Using a single machine limits both reliability and scalability.
Scalability is completely dependent on how powerful the single machine can become. Multiple front-end machines with http request load balancing is more reliable, but the cafe, database machine is clinical support study, still a single point of failure. A database caching layer in the servlet helps performance. An EJB caching layer is difficult to cafe cover, achieve. On Wilderness. Oracle 9i includes queryable snapshots of the cafe cover, main database which can offload the query to run against the clients local snapshot. An in-memory database (such as TimesTen) is very, very fast and can act as a queryable cache for a back end database. Clinical Decision Support System Case Study. Database instances on each machine, with replication increases reliability and letter access speed.
But updates now need to to the, be handled differently. Cafe Cover Letter. Alternatives include: buffering updates; using message queues; database update replication. Partitioning the once to the lake, database across multiple machines adds scalability, but must be done with care. If you want very reliable systems then everything has to cover, be controlled. A load balancing message queue may be needed for a high rate of messages (500/sec). Note that reliable systems should ensure that all duplicated data have no single points of lake, failure in cafe, the software or hardware chain behind the paper and science, data (different controllers, UPSs, etc). Techniques to avoid deadlocks (Page last updated September 2001, Added 2001-10-22, Author Mark Dykstra, Publisher Java Developers Journal). Tips: Potential deadlocks can be caused by letter, coding styles. Always acquire a set of locks in the same set order.
Don't hold a lock and clinical system study wait for an event. Specify which thread should have access to letter, data at effect essay addiction any time. Ensure that both access and cafe cover update to essays on wilderness, the same variable is synchronized on the same monitor. Stateful to Stateless Bean (Page last updated February 2002, Added 2002-03-25, Author Brett McLaughlin, Publisher OnJava). Tips: Stateless session beans are much more efficient than stateful session beans.
Stateless session bean have no state. Most containers have pools of cafe cover letter, stateless beans. Each stateless bean instance can serve multiplw clients, so the bean pool can be kept small, and doesn't need to change in size avoiding the effect essay, main pooling overheads. A separate stateful bean instance must exist for cafe letter, every client, making bean pools larger and more variable in size. [Article discusses how to decision support system case, move a stateful bean implementation to stateless bean implementtaion]. Alternatives to using 'new'. (Page last updated March 2002, Added 2002-03-25, Author Jonathan Amsterdam, Publisher Dr. Dobb's). Tips: The 'new' operator is not object oriented, and prevents proper polymorphic object creation. Constructors must be made non-public and preferably private to cafe cover letter, limit the number of objects of a class. Eb White Essay To The. The Singleton pattern and the Flyweight (object factory) pattern are useful to limit numbers of objects of various types and to assist with object reuse and reduce garbage collection. The real-time specification for Java allows 'new' to allocate objects in a 'current memory region', which may be other than the heap.
Each such region is a type of MemoryArea, which can manage allocation. Using variables to provide access to limited numbers of cafe cover, objects is essay on technology, efficient, but a maintenance problem if you need to change the object access pattern, for example from a global singleton to a ThreadLocal Singleton. A non-static factory method is polymorphic and so provides many advantages over cafe cover letter, static factory methods. The Abstract Factory design pattern uses a single class to create more than one kind of object. An alternative to the Flyweight pattern is the Prototype pattern, which allows polymorphic copies of existing objects. The Object.clone() method signature provides support for the Prototype pattern.
Prototypes are useful when object initialization is expensive, and you anticipate few variations on essays on wilderness the initialization parameters. Then you could keep already-initialized objects in a table, and clone an existing object instead of expensively creating a new one from scratch. Immutable objects can be returned directly when using Prototyping, avoiding the copying overhead. Timing out cover letter sockets (Page last updated 2000, Added 2001-06-18, Author David Reilly, Publisher JavaCoffeeBreak). Tips: Use a timer thread to monitor socket activity and timeout if blocked.
Use the cause effect essay addiction, socket option SO_TIMEOUT, set by using the cafe cover letter, setSoTimeout() method, to automatically timeout blocked sockets. Deadlocks (Page last updated November 2000, Added 2002-04-26, Author Heinz M. Kabutz, Publisher Kabutz). Tips: Use CTRL+BREAK to get a thread dump when a deadlock occurs, to find where the deadlock is. Eb White Essay More To The Lake. Use SwingUtlities.invokeLater() to run any Swing GUI changes and avoid deadlocks, but note that this will hold up GUI processing while running, so make the run() call quick. Use SwingUtilities.isEventDispatchThread() to test if can run code immediately without calling SwingUtlities.invokeLater(). Load testing of web applications (Page last updated June 2001, Added 2001-06-18, Author Frank Cohen, Publisher IBM).
Tips: Current Web-application architectures consists many small servers that are accessed through a load balancer, providing a front-end to a powerful database server. This architecture provides a foundation for achieving good performance. Cafe Cover Letter. Load testing of web applications should include: State machine testing (entries in a shopping basket, should still be there when checked out); Really long session testing (session started then continued several hours later); Hordes of what i did break essay, savage users testing (users do lots nonsensical activity); Privileged testing (only some users should be able to access some functionality); Speed testing (do tasks complete within the required times?). Each type of test should be run with several different user loads. Test suites should be automated and easily changed. [Article discusses Load , an open-source set of tools with XML scripting language] J2EE design patterns to improve performance (Page last updated June 2001, Added 2001-06-18, Author Daniel H. Steinberg, Publisher JavaWorld). Tips: Combine multiple remote calls for state information into one call using a value object to wrap the data (the Value Object pattern, superceded by local interfaces in EJB 2.0).
Where long lists of data are returned by queries, use the Page-by-Page Iterator pattern: a server-side object that holds data on the server and supplies batches of results to the client. Oracle JDBC tips (Page last updated December 2001, Added 2001-12-26, Author Donald Bales, Publisher OnJava). Tips: Although Oracle recommend using the OCI driver for optimal client side access, the writer finds the Thin driver to have have better performance. Turn off autocommit, Connection.setAutoCommit(false). From the cover letter, client side, Statement is cause effect, faster than PreparedStatement (except if you are batching statements) when using dynamic SQL. Use PreparedStatements for all, except dynamic, SQL statements. Use PreparedStatements for batching repetitive inserts or updates. OraclePreparedStatement.setExecuteBatch() (proprietary method) is the fastest way to cover, execute batch statements. Use SQL's set based processing capabilities to operate on multiple rows simultaneuosly, rather than blindly operating on one row at a time as the what essay, simplest Java-RDB architectural mapping will produce. Chapter 19, Performance of Java Programming with Oracle JDBC (Page last updated December 2001, Added 2001-12-26, Author Donald Bales, Publisher O'Reilly). Tips: Performance should be considered at the start of a project.
Use the EXPLAIN PLAN facility to explain how the database's optimizer plans to execute your SQL statements, to identify performance improvements such as additional indexes. If more than one SQL statement is letter, executed by your program, you can gain a small performance increase by turning off auto-commit. It takes about 65 iterations of a prepared statement before its total time for execution catches up with a statement, because of prepared statement initialization overheads. Use PreparedStatements to batch statements for optimal performance. The Thin driver is faster than the OCI driver. This is contrary to Oracle's recommendation. A SELECT statement makes two round trips to the database, the first for metadata, the second for essays, data. Cover. Use OracleStatement.defineColumnType() to predefine the SELECT statement, thus providing the JDBC driver with the decision support case, column metadata which then doesn't require the first database trip.
Given a simple SQL statement and a stored procedure call that accomplishes the cafe cover, same task, the eb white essay once to the lake, simple SQL statement will always execute faster because the stored procedure executes the same SQL statement but also has the overhead of the procedure call itself. On the other hand complex tasks requiring several SQL statements can be faster using stored procedures as fewer network trips and data transfers will be needed. Database performance (Page last updated December 2001, Added 2001-12-26, Author Peter Varhol, Publisher JavaPro). Tips: Thoughtful page design makes for a better user experience by enabling the letter, application to seem faster than it really is. Effect Essay Computer Addiction. Use the flush method associated with the cover letter, out object to display static text and graphics on the browser page before the database query returns, to decision system study, prevent the user from having to look at a blank page for a long time. ResultSet types affect updates.
TYPE_FORWARD_ONLY: no updating allowed; TYPE_SCROLL-SENSITIVE: update immediately; TYPE_SCROLL_INSENSITIVE: update when the connection is closed. (Concurrency type must be set to CONCUR-UPDATABLE to allow the table to be updated.) Performance can be better if changes to the database are batched: turn off autocommit; add multiple SQL statements using the cafe letter, Statement.addBatch() method; execute Statement.executeBatch(). Scaled systems need optimized SQL calls, querying the in younger, right amount of data, and displaying pages before the query is complete. Prepared statements also speed up database access, and letter should be used if a statement is to be executed more than once. JDBC tutorial (requires free registration) (Page last updated November 2001, Added 2001-12-26, Author Robert J. Brunner, Publisher IBM). Tips: Type 1 (JDBC-ODBC-DB) drivers incur a performance penalty because of the bridging needed to reach the database. [Type 2 (JDBC-clientDBAgent-DB) drivers seem to i did, have middling performance]. Type 3 (JDBC-Middleware-DB) drivers incur a performance penalty because of the bridging needed to cafe letter, reach the database, but does introduce optimization potential from the location of the middleware. Type 4 (JDBC-DB) drivers typically provide optimum driver performance.
The higher the level of transaction protection, the higher the decision support study, performance penalty. Transaction levels in order of increasing level are: TRANSACTION_NONE, TRANSACTION_READ_UNCOMMITTED, TRANSACTION_READ_COMMITTED, TRANSACTION_REPEATABLE_READ, TRANSACTION_SERIALIZABLE. Use Connection.setTransactionIsolation() to cafe, set the computer, desired tansaction level. The default autocommit mode imposes a performance penalty by making every database command a separate transaction. Turn off autocommit (Connection.setAutoCommit(false)), and explicitly specify transactions. Batch operations by cafe, combining them in one transaction, and in one statement using Statement.addBatch() and Statement.executeBatch(). Savepoints (from JDBC3.0) require expensive resources. Release savepoints as soon as they are no longer needed using Connection.releaseSavepoint(). Each request for a new database connection involves significant overhead. This can impact performance if obtaining new connections occurs frequently. Reuse connections from connection pools to essay once more to the, limit the cafe, cost of creating connections. [The tutorial lists all the overheads involved in creating a database connection].
The ConnectionPoolDataSource (from JDBC3.0) and PooledConnection interfaces provide built-in support for connection pools. Use setLogWriter() (from Driver, DataSource, or ConnectionPooledDataSource; from addiction, JDBC3.0) to help trace JDBC flow. Use Connection.setReadOnly(true) to optimize read-only database interactions. Use Connection.nativeSQL() to see how the SQL query will execute in the database to help ensure that the SQL is cafe, optimized. Advanced JDBC tutorial (requires free registration). (Page last updated November 2001, Added 2001-12-26, Author Robert J. Brunner, Publisher IBM).
Tips: PreparedStatement objects are compiled (prepared) by the JDBC driver or database for faster performance, and accept input parameters so they can be reused with different data. Stored procedures are functions that execute inside a database which provides faster performance than plain SQL. Java supports stored procedures from CallableStatement objects. Performance optimizing design patterns for J2EE (Page last updated December 2001, Added 2001-12-26, Author Vijay Ramachandran, Publisher Sun). Tips: For read-only access to a set of data that does not change rapidly, use the Fast Lane Reader pattern which bypasses the EJBs and uses a (possibly non-transactional) data access object which encapsulates access to system, the data. Cafe Letter. Use the essays on wilderness, Fast Lane Reader to read data from the server and display all of cafe letter, them in i did on spring break essay, one shot. Cafe Letter. When you need to access a large remote list of paper and science, objects, use the Page-by-Page Iterator pattern which sends smaller subsets of the data as requested until the client no longer want any more data. Use the Page-by-Page Iterator to send lists of simple objects from EJBs to clients.
When the cover, client would request many small data items which would require many remote calls to survival, satisfy, combine the multiple calls into one call which results in a single Value Object which holds all the data required to be transferred. Cafe Cover Letter. Use the Value Object to send a single coarse-grained object from the server to what i did break essay, the client(s). Flicker-free graphics with the Mobile Information Device Profile (Page last updated July 2001, Added 2001-08-20, Author Eric Giguere, Publisher Sun). Tips: Use double buffering: draw into an offscreen buffer, then copy into cafe the display buffer. Copying buffers is very fast on most devices, while directly drawing to a display sometimes causes users to see a flicker, as individual parts of the cause addiction, display are updated. Double buffering avoids flickering by combining multiple individual drawing operations into a single copy operation. Cafe Letter. Use the essays survival, Canvas.isDoubleBuffered() method, to determine if double buffering is cover, already automatically used: on some implementations the Canvas object's paint method is already a Graphics object of an offscreen buffer managed by essays survival, the system. (The system then takes care of copying the offscreen buffer to cover letter, the display.) Use javax.microedition.lcdui.Image class to create an offscreen memory buffer, and use Graphics to draw to the offscreen buffer and to copy the contents of the offscreen buffer onto decision system case study the display. Cafe Letter. The offscreen buffer is created by calling one of the Image.createImage methods.
Double buffering does have some overhead: if only eb white to the lake, making small changes to cafe letter, the display, it might be slower to use double buffering. Essay Computer. On some systems image copying isn't very fast and cafe letter flicker can can happen even with double buffering. Keep the number of offscreen buffers to essay generation, a minimum. Cafe Letter. There is a memory penalty to pay for essay in younger, double buffering: the offscreen memory buffer can consume a large amount of memory. Free the letter, offscreen buffer whenever the canvas is hidden (use the canvas' hideNotify() and showNotify() methods.) Some killer quotes, leading to the odd tip. (Page last updated 2000, Editor Elliotte Rusty Harold, Publisher IBiblio).
Tips: A Vector may be convenient and generalized, but it's almost always overkill, and you pay the price for it in speed and other ways. On Technology And Fitness In Younger. --Greg Guerin on the MRJ-dev mailing list A lot of speed (or memory) can go down the drain if the cover letter, underlying structure is a poor fit to the problem, or is decision study, inefficient for cafe letter, a particular program's common actions. --Greg Guerin on essay on technology the MRJ-dev mailing list It is perfectly legal for available() to always return 0, even when there are a zillion bytes available, and in fact the cafe cover letter, default implementation in Inputstream.available() does just that. Research Paper On Religion And Science. --Thomas Maslen on the mrj-dev mailing list Seeing the cover letter, wrong solution to a problem (and understanding why it is wrong) is often as informative as seeing the correct solution. --W. Richard Stevens You need to on technology in younger, run your full QA cycle on _all_ platforms you plan on cafe cover supporting your app on . real software releases need to be tested on a large variety of and science, different systems and cafe OS versions because there _are_ differences. Essays. Just like there are differences between different Java implementations. --Jens Alfke on the mrj-dev mailing list I often find with Java that if you run the same program twice, the second run is significantly faster, presumably because the JVM is remembering something. Cover Letter. --Michael Kay on the xsl-list mailing list Java isn't inherently slow, it just encourages a create and forget [objects] type of programming which is. --Oren Ben-Kiki on the XSL mailing list Java does not expose many of the I/O capabilities that are synonymous with high performance. Examples include memory mapped files and asynchronous I/O. Heck, it doesn't even expose non-blocking I/O. --Gabe Beged-Dov on the xml-dev mailing list I/O performance issues, usually overshadow all other performance issues making them the first area to concentrate on when tuning performance. Unfortunately, optimal reading and writing can be challenging in Java. --Daniel Lord and Achut Reddy, http://www.sun.com/workshop/java/wp-javaio/ Streamlining the use of I/O often results in greater performance gains than all other possible optimizations combined. --Daniel Lord and research and science Achut Reddy http://www.sun.com/workshop/java/wp-javaio/ Modern super-scalar processors with deep memory hierarchies and complex compiler optimization stages make it *extremely* difficult to predict which code or data structure variant is more efficient.
Old rules of thumb and common sense are not of much use any more for distinguishing more and less performant algorithms of cafe cover letter, comparable complexity on a late 1990s processor. Surprises are frequent. Design decisions on performance grounds should today only be made after real measurements and much of what you learned 10 years ago about manual optimization is obsolete these days. --Markus Kuhn on and fitness in younger generation the Unicode mailing list Most Java VM implementations search the interface list back to front so that most often used interface should be the last interface in the 'implements' list. --Don Park on the xml-dev mailing list. Article about optimizing I/O performance. Cover. (Page last updated November 2000, Added 2000-12-20, Author Brian Goetz, Publisher JavaWorld). Tips: Measure early, measure often. Cause Effect Essay Addiction. You can't effectively manage performance if you don't know the source of your problem. Spending days tuning a subsystem that accounts for 1 percent of an application's total runtime simply cannot yield more than a 1 percent improvement in application performance. Use performance measurement tools to identify where your application spends its time and focus your energy on those hot spots. Object creation is an expensive operation: avoid excessive object instantiations. Use buffered I/O (with buffering classes or by explicitly buffering to an array). InputStream runs faster than Reader.
Combine tasks from multiple classes to avoid extra overhead and redundant object creation. Particle's pretty good coverage of the cover, main Java data structures. What On Spring Break. Only a few tuning tips: reuse, pools, optimized sorting. But knowing which structure to letter, use for decision support system study, a particular problem is an important performance tuning technique. (Page last updated April 2000, Added 2000-12-20, Author J. Particle, Publisher Particle). Tips: Make linked lists faster by cafe cover letter, having dummy first and clinical system study last nodes. Reusing code is easier than reimplementing, but can lead to slower performance. Use node pools to reduce memory impact. Sorting elements on insertion means they don't need to cover letter, be sorted later. [Article includes several(non-optimized) standard sort algorithms implemented in Java, and compares their performance.] [Article discusses optimizing a quicksort.] If you are using many small collections, carefully consider the collection structure used. Some structures may have large memory overheads that should be avoided in this case. Some discussion of hidden surface removal for graphics.
Article on essay on technology recycling resource pools (Page last updated 1998, Added 2000-12-20, Authors Philip Bishop and Nigel Warren, Publisher JavaWorld). Tips: Check for broken resources when putting them back in the pool. Use the builder pattern: break the construction of cover, complex objects into a series simpler Builder objects, and a Director object which combines the Builders to form the complex object. Then you can use Recycler (a type of Director) to replace only the broken parts of the complex object, so reducing the amount of objects that need to be recreated. Article on building an object pool for improved performance. (Page last updated June 1998, Added 2000-12-20, Author Thomas E. Davis, Publisher JavaWorld). Tips: [Article discusses generic pool issues including storage, tracking, and expiration times of pool elements.] Use connection pools to recycle connections and reduce overheads [Article includes a JDBC connection pool implementation.] Article on improving object pools performance. (Page last updated September 1998, Added 2000-12-20, Author Thomas E. Davis, Publisher JavaWorld). Eb White Essay Once More To The Lake. Tips: Use an expiration thread to clean up excessive amounts of objects in the pool. Use java.lang.ref.Reference objects to cover, determine when objects checked out but never checkd in have been released by system study, the application.
Limiting the size of the pool can adversely impact performance. Optimizing JDBC (Page last updated August 2001, Added 2001-08-20, Author John Goodson, Publisher Java Developers Journal). Cafe Cover. Tips: Minimize the use of essay generation, Metadata: Cache all metadata as they will not change; Avoid using null arguments in metadata methods; Use a dummy query with getMetadata() rather than getColumns(). Retrieve data as efficiently as possible: Minimize the amount of data returned by the query; Don't make average users pay the same query cost of the cover letter, users with extensive query requirements; Remember that users seldom want to see too much data in one go; Use setMaxRows(), setMaxFieldSize(), and decision case study SetFetchSize(); Decrease the column size; Use the smallest packet size that will meet your needs (if the driver supports packet sizing). Use a parametrized remote procedure call (RPC) rather than passing parameters as part of the RPC call, e.g. Cover Letter. use Connection.prepareCall(Call getCustName (?)).setLong (1,12345) rather than Connection.prepareCall(Call getCustName (12345)) Minimize connections; try to reuse connections. Turn autocommit off. Essays Survival. Avoid using distributed transactions. Cafe Cover Letter. Use getBestRowIndentifier() to determine the optimal set of columns to use in the Where clause for updating data. (The columns returned could be pseudo-columns that can provide pointers to the exact location of the data, and essay on technology in younger are not obtained by getColumns().) EJB performance tips (Page last updated November 2001, Added 2001-12-26, Authors Ravi Kalidindi and Rohini Datla, Publisher PreciseJava). Tips: EJB calls are expensive.
A method call from the client could cover all the following: get Home reference from the NamingService (one network round trip); get EJB reference (one or two network roundtrips plus remote creation and initialization of cafe cover, Home and EJB objects); call method and return value on once more lake EJB object (two or more network rountrips: client-server and [mutliple] server-db; several costly services used such as transactions, persistence, security, etc; multiple serializations and letter deserializations). If you don't need EJB services for an object, use a plain Java object and not an decision support EJB object. Use Local interfaces (from EJB2.0) if you deploy both EJB Client and EJB in the same JVM. (For EJB1.1 based applications, some vendors provide pass-by-reference EJB implementations that work like Local interfaces). Wrap multiple entity beans in a session bean to change multiple EJB remote calls into one session bean remote call and several local calls (pattern called SessionFacade). Change multiple remote method calls into cafe cover letter one remote method call with all the data combined into a parameter object. Control serialization by modifying unnecessary data variables with 'transient' key word to effect, avoid unnecessary data transfer over cafe, network. Cache EJBHome references to avoid JNDI lookup overhead (pattern called ServiceLocator).
Declare non-transactional methods of session beans with 'NotSupported' or 'Never' transaction attributes (in the ejb-jar.xml deployment descriptor file). Transactions should span the minimum time possible as transactions lock database rows. Set the transaction time-out (in the ejb-jar.xml deployment descriptor file). Use clustering for scalability. Tune the EJB Server thread count. Use the HttpSession object rather than a Stateful session bean to maintain client state. Use the ECperf benchmark to help differentiate EJB server performances. Tune the Stateless session beans pool size to minimize the creation and destruction of essay addiction, beans. Use the setSessionContext() or ejbCreate() method to cache bean specific resources. Release acquired resources in the ejbRemove() method.
Tune the letter, Stateful session beans cache size to and time-out minimize activations and passivations. Essay On Technology In Younger Generation. Allow stateful session beans to be removed from the container cache by explicitly using the remove() method in the client. Tune the cafe letter, entity beans pool size to minimize the survival, creation and cover letter destruction of beans. Tune the entity beans cache size to minimize the activation and passivation of beans (and associated database calls). Use the essays survival, setEntityContext() method to cafe cover, cache bean specific resources and release them from the eb white essay lake, unSetEntityContext() method. Use Lazy loading to avoid unnecessary pre-loading of child data. Choose the lowest cost transaction isolation level that avoids corrupting the data.
Transaction levels in increasing cost are: TRANSACTION_READ_UNCOMMITED, TRANSACTION_READ_COMMITED, TRANSACTION_REPEATABLE_READ, TRANSACTION_SERIALIZABLE. Use the lowest cost locking available from the database that is cafe letter, consistent with any transaction. Create read-only entity beans for read only operations. Research And Science. Use a dirty flag where supported by the EJB server to avoid writing unchanged EJBs to the database. Commit the data after the transaction completes rather than after each method call (where supported by EJB server). Do bulk updates to reduce database calls. Cafe Letter. Use CMP rather than BMP to utilize built-in performance optimization facilities of CMP. Use ejbHome() methods for global operations (from EJB2.0). Tune the connection pool size to minimize the creation and destruction of database connections.
Use JDBC directly rather than using entity beans when dealing with large amounts of data such as searching a large database. Combine business logic with the entity bean that holds the data needed for that logic to process. Tune the Message driven beans pool size to optimize the concurrent processing of messages. Use the setMesssageDrivenContext() or ejbCreate() method to cache bean specific resources, and eb white once more to the lake release those resources from the ejbRemove() method. JDBC performance tips (Page last updated November 2001, Added 2001-12-26, Authors Ravi Kalidindi and cafe cover Rohini Datla, Publisher PreciseJava). Tips: Use the fastest driver available to the database: normally type 4 (preferably) or type 3. Tune the i did on spring break essay, defaultPrefetch and defaultBatchValue settings. Get database connections from a connection pool: use javax.sql.DataSource for cafe cover, optimal configurability.
Use the essays survival, vendor's connection pool; or ConnectionPoolDataSource and PooledConnection from cafe cover, JDBC2.0; or a proprietary connection pool. More Lake. Batch your transactions. Turn off autocommit and explicitly commit a set of statements. Cafe Cover. Choose the fastest transaction isolation level consistent with your application requirements. Levels from fastest to essay, slowest are: TRANSACTION_NONE, TRANSACTION_READ_UNCOMMITED, TRANSACTION_READ_COMMITED, TRANSACTION_REPEATABLE_READ, TRANSACTION_SERIALIZABLE. Close resources (e.g. connections) when finished with them.
Use a PreparedStatement when you execute the same statement more than once. Use CallableStatement to execute stored procedures. Letter. This is faster than a prepared statement, but loses database independence (stored procedures are not standardized unlike SQL). Batch updates and accesses with Statements and ResultSets (with executeBatch() and setFetchSize()). Set up the proper direction for processing rows. Use the proper getXXX() methods. Write SQL queries that minimize the in younger, data returned. Cache read-only and cover read-mostly tables data. Use the Page-by-Page Iterator pattern to more lake, repeatedly pass small amounts of cafe, data rather than huge chunks. Servlet performance tips (Page last updated November 2001, Added 2001-12-26, Authors Ravi Kalidindi and Rohini Datla, Publisher PreciseJava).
Tips: Use the servlet init() method to cache static data, and release them in the destroy() method. Use StringBuffer rather than using + operator when you concatenate multiple strings. Use the print() method rather than the println() method. Use a ServletOutputStream rather than a PrintWriter to send binary data. Initialize the PrintWriter with the eb white essay once lake, optimal size for pages you write. Flush the cafe cover, data in sections so that the user can see partial pages more quickly.
Minimize the synchronized block in the service method. Essays. Implement the getLastModified() method to use the browser cache and the server cache. Use the application server's caching facility. Session mechanisms from fastest to slowest are: HttpSession, Hidden fields, Cookies, URL rewriting, the persistency mechanism. Remove HttpSession objects explicitly in your program whenever you finish the session. Set the session time-out value as low as possible. Use transient variables to reduce serialization overheads.
Disable the servlet auto reloading feature. Cover. Tune the thread pool size. High load web servlets (Page last updated July 2002, Added 2002-07-24, Author Pier Fumagalli, Publisher OnJava). Tips: Hand off requests for static resources directly to cause computer addiction, the web server by specifying the URL, not by redirecting from the servlet. Use separate webservers to deliver static and cafe cover dynamic content. Cache as much as possible. Make sure you know exactly how much RAM you can spare for essays on wilderness, caches, and have the right tools for measuring memory. Load balance the Java application using multiple JVMs.
Use ulimit to monitor the number of file descriptors available to the processes. Make sure this is high enough. Cafe Cover Letter. Logging is essay computer addiction, more important than the performance saved by not logging. Cafe Cover. Monitor resources and prepare for essay generation, spikes. JSP performance tips (Page last updated November 2001, Added 2001-12-26, Authors Ravi Kalidindi and Rohini Datla, Publisher PreciseJava). Tips: Use the jspInit() method to cache static data, and release them in cafe cover, the jspDestroy() method. Use the jspInit() method to cache static data. Use StringBuffer rather than using + operator when you concatenate multiple strings. Use the print() method rather than the println() method.
Use a ServletOutputStream rather than a PrintWriter to send binary data. Support Case Study. Initialize the PrintWriter with the cafe cover letter, optimal size for on technology and fitness in younger generation, pages you write. Letter. Flush the data in sections so that the user can see partial pages more quickly. Minimize the cause effect essay computer addiction, synchronized block in the service method. Avoid creating a session object with the directive %@ page session=false % Increase the buffer size of cover letter, System.out with the directive %@ page buffer=12kb % Use the include directive instead of the include action when you want to include another page. Minimize the scope of the 'useBean' action. Custom tags incur a performance overhead. Use as few as possible.
Use the application server's caching facility, and the session and application objects (using getAttribute()/setAttribute()). There are also third-party caching tags available. Session mechanisms from on technology and fitness generation, fastest to cover, slowest are: session, Hidden fields, Cookies, URL rewriting, the persistency mechanism. Remove 'session' objects explicitly in your program whenever you finish the session. Reduce the session time-out as low as possible.
Use 'transient' variables to i did break, reduce serialization overheads. Cafe Cover. Disable the JSP auto reloading feature. Tune the thread pool size. JMS performance tips (Page last updated November 2001, Added 2001-12-26, Authors Ravi Kalidindi and essays on wilderness survival Rohini Datla, Publisher PreciseJava). Tips: Start the consumer before you start the producer so that the cover letter, initial messages do not need to queue. Clinical Decision System Case. Use a ConnectionConsumer to process messages concurrently with a ServerSessionPool. Close resources (e.g. connections, session objects, producers, consumers) when finished with them. DUPS_OK_ACKNOWLEDGE and cover letter AUTO_ACKNOWLEDGE perform better than CLIENT_ACKNOWLEDGE.
Use separate transactional sessions and non-transactional sessions for transactional and essays on wilderness non-transactional messages. Tune the Destination parameters: a smaller capacity increases message throughput; a higher redelivery delay and lower redelivery limit reduces the overhead. Cafe Cover Letter. Choose non-durable (NON_PERSISTENT) messages wherever appropriate to and fitness, avoid the persistency overhead. Set the TimeToLive value as low as feasible (default is for messages to never expire). Receive messages asynchronously with a MessageListener implementation. Choose the letter, message type that minimizes memory overheads. Use 'transient' variables to reduce serialization overheads. Pattern performance tips (Page last updated November 2001, Added 2001-12-26, Authors Ravi Kalidindi and Rohini Datla, Publisher PreciseJava). Tips: The ServiceLocator/EJBHomeFactory Pattern reduces the expensive JNDI lookup process by caching EJBHome objects. The SessionFacade Pattern reduces network calls by combining accesses to multiple Entity beans into one access to the facade object.
The MessageFacade/ServiceActivator Pattern moves method calls into a separate object which can execute asynchronously. Clinical Support Study. The ValueObject Pattern combines remote data into one serializable object, thus reducing the number of network transfers required to access multiple items of remote data. The ValueObjectFactory/ValueObjectAssembler Pattern combines remote data from multiple remote objects into one serializable object, thus reducing the number of network transfers required to access multiple items of remote data. The ValueListHandler Pattern: avoids using multiple Entity beans to access the database, using Data Access Objects which explicitly query the database; and returns the data to cover, the client in batches (which can be terminated) rather than in one big chunk, according to on technology generation, the Page-by-Page Iterator pattern. The CompositeEntity Pattern reduces the number of actual entity beans by wrapping multiple java objects (which could otherwise be Entity beans) into cafe cover letter one Entity bean.
Writing a seamless audio looper (Page last updated August 2001, Added 2001-08-20, Author Greg Travis, Publisher EarthWeb). Research Paper On Religion. Tips: Switching audio streams from one piece of sound to another requires some fiddly managing of the transition delay in cover letter, order to avoid a gap in the audio output. To avoid the transition delay, you need to: flush the output buffer; find out how much data was dumped; add a fudge factor; and combine these values to determine from where to start playing the new audio stream. Generating code dynamically (Page last updated February 2002, Added 2002-02-22, Author Norman Richards, Publisher Java Developers Journal). Tips: Compiling code into classes at runtime, such as for JSP pages, provides excellent flexibility with almost no performance overhead. XSLTC can compile XSL stylesheets to system case, speed up transforming XML input files.
If a complex interpreted procedure is expected to be used more than once, it can be more efficient to convert the procedure into an expression tree which will apply the cover, procedure optimally. Paper. Converting a complex interpreted procedure into code that can be compiled, then using a compiled version normally results in the fastest execution times for the procedure. Sun's javac is not a very efficient compiler. Faster compilers are available, such as jikes. Compiling code at runtime can take a significant amount of cafe, time. If the research paper, compile time needs to cafe cover letter, be minimized, it is what on spring, important to use the cafe, fastest compiler available. An in-memory compiler is on spring break, significantly faster than compiling code using an external out-of-process Java compiler.
Generating bytecode directly in-process is significantly faster than compiling code using an letter external out-of-process Java compiler, and is also faster than using an in-memory compiler. BCEL, the Bytecode Engineering Library, is one possible bytecode generator. Java 3D performance tips (Page last updated June 2001, Added 2001-08-20, Author Doug Twilleager, Publisher J3D). Tips: Once an application calls BranchGroup.compile() or SharedGroup.compile(), only objects with their capability bits set can be modified. Use capability bits to paper and science, describe which objects change at runtime, so that J3D can optimize the app.
Only set capability bits when needed, to let J3D maximally optimize performance. Set the letter, bounds of objects so that J3D can ignore objects outside target object spatial scopes. Reorder leaf nodes for the most efficient rendering. When rendering check only the changes in rendering characteristics rather than all characteristics. Minimize the number of Shape3D nodes, but don't combine while ignoring spatial locality. Use the stripifier, or manually stripify the application: try to convert the geometry into long strips of eb white essay lake, triangles rather than fans of triangles. Cafe. Share Appearance/Texture/Material NodeComponent objects when possible. Set the essays survival, thread priorities appropriately, or use the default priority. Minimize thread activity.
Note the performance effects of the J3D threads, specifically Behaviors, Collision and Sounds. Cover. J3D fully supports multi-processor machines. Use native threads where possible. Use application knowledge to clinical support case study, turn off currently non-visible Switch nodes. Use a Switch node to animate a sprite by putting all the animation frames under one Switch node and using a SwitchValueInterpolator. This increases memory consumption in cover letter, favor of what i did on spring break, smooth animations. Unordered groups are faster than ordered groups. LOD Behaviors can be to reduce geometry rendering requirements with lower levels of detail. Use bounds based picking rather than geometry based picking. Transform the ViewPlatform rather than every object for a scene transformation. The Verified Service Locator pattern (Page last updated July 2002, Added 2002-07-24, Author Paulo Caroli, Publication JavaWorld, Publisher JavaWorld).
Tips: The Service Locator pattern improves performance by caching service objects that have a high-lookup cost. The Service Locator pattern has a problem in that cached objects may become invalid without the service locator knowing. The Verified Service Locator pattern periodically tests the validity of the caches objects to avoid providing invalid service objects to requestors. Sun Community chat on cover letter Java BluePrints (Page last updated May 2002, Added 2002-07-24, Author Edward Ort, Publication Sun Developer, Publisher Sun). Effect Addiction. Tips: For very large transactions, use transaction attribute TX_REQUIRED for EJB methods to have all the cafe cover letter, method calls in a call chain use the research paper on religion, same transaction.
Make tightly coupled components local to each other. Put remote beans primarily as facades across subsystems. The page-by-page pattern is cafe letter, designed to handle cases where the result set is large, and the end-user is not interested in seeing all of the eb white essay once lake, results. There is really no upper threshold for the size of result set in the pattern. Clustering with JBoss (Page last updated July 2002, Added 2002-07-24, Authors Bill Burke, Sacha Labourey, Publisher OnJava). Tips: A hardware- or software-based HTTP load-balancer usually sits in front of the application servers within a cluster. The load balancer can decrypt HTTPS requests and cafe cover letter distribute load.
HTTP session replication is expensive for a J2EE application server. If you can live with forcing a user to log in again after a server failure, then an HTTP load-balancer probably provides all of the what on spring break, fail-over and load-balancing functionality you need. If you are storing things other than EJB Home references in your JNDI tree, then you may need clustered JNDI. 24/7 availability needs the cover letter, ability to essay on technology generation, hot-deploy and undeploy new applications and new versions, and to apply patches, without bringing down the application server for cover letter, maintenance. Cause. Smart proxies can be used to implement load-balancing and cafe cover letter fail-over for EJB remote clients. These proxies manage a list of available RMI connections one of which it will use to clinical decision support system case, service an invocation. Speeding web page downloads using compression (Page last updated July 2002, Added 2002-07-24, Author Steven Chau, Publication HttpRevealer.com, Publisher HttpRevealer.com). Cafe Cover Letter. Tips: Browsers sending Accept-Encoding: gzip will accept gziped compressed pages. Return the page compressed with Content-Encoding: gzip using GZIPOutputStream. Use a servlet filter to transparently compress pages to browsers that accept compressed pages. Optimizing JDBC Prepared Statments.
Also a followup discussion at http://www.theserverside.com/discussion/thread.jsp?thread_id=8013 (Page last updated July 2001, Added 2001-08-20, Author ?, Publisher The Server Side). Tips: Databases analyze query statements to decide how to process them most optimally, then cache the resulting query plan, keyed on the full statement. Reusing identical statements reuses the query plan. Altering the statement causes a new query plan to be generated for each new statement. Essay On Technology In Younger. However statements with parameters can have the query plan reused, so use parameters rather than regenerating the statement with different values. Using a new connection requires a prepared statement to cafe letter, be recreated. Reusing connections allows a prepared statement to be reused.
Connection pools should have associated PreparedStatement caches so that the PreparedStatements are automatically reused. Swing performance tips (Page last updated 1999, Added 2001-05-21, Author Bill Harlan, Publisher Harlan). Tips: Redraw events can easily be generated faster than the computer, redraw can execute. Cafe Letter. Ignore redraw events (or block their generation) until the current redrw is finished. Research Paper On Religion And Science. Don't up redraw events.
Consider holding redraw events for cover, a few milliseconds to see if it can be discarded due to clinical decision support case, getting another redraw event. If possible, consider drawing to off-screen buffers, and execute copies from that buffer in response to redraws, rather than actualy redrawing. Extend from cafe cover letter, JPanel, not Canvas; override paintComponent(), not paint(). Action listeners are all executed in the one event-dispatching thread. Time-consuming listeners should execute their work in a separate thread and should avoid blocking the event-dispatching thread. (To reenter the event-dispatching thread calling SwingUtilities.invokeLater() or invokeAndWait()). Add event listeners after initialization of effect addiction, components have finished. Swing performance tips (Page last updated March 2001, Added 2001-05-21, Author Steve Wilson, Publisher Sun). Tips: Use the latest version of cafe, Swing available, as the Swing development team have an ongoing project tp improve performance. On Technology Generation. When JScrollPane is scrolled, the entire visible contents of the scroll pane are redrawn. A backing store (off screen buffer) can be enabled using setBackingStoreEnabled(true) to speed up redraws, but this has some limitations: an extra buffer to copy can be significant for simple drawing operations; the cover, backing store doesn't work when scrollRectToVisible() is called directly by cause effect addiction, the programmer (depends on Swing version); extra RAM is needed to maintain the cover letter, extra backing buffer. Use window blitting (may be default depending on Swing version) enabled with scrollpane.getViewport().putClientProperty(EnableWindowBlit, Boolean.TRUE).
Enable outline dragging (no redrawing while dragging) with JDesktopPane.putClientProperty(JDesktopPane.dragMode, outline). Enable faster dragging using blitting with JDesktopPane.putClientProperty(JDesktopPane.dragMode, faster). Chapter 10, Serialization from Java RMI (Page last updated November 2001, Added 2001-12-26, Author William Grosso, Publisher OnJava). Survival. Tips: Use transient to cafe cover, avoid sending data that doesn't need to clinical system case, be serialized. Cover Letter. Serialization is a generic marshalling mechanism, and essays on wilderness generic mechanisms tend to be slow. Serialization uses reflection extensively, and cover letter this also makes it slow. Serialization tends to generate many bytes even for small amounts of research paper on religion and science, data.
The Externalizable interface is provided to solve Serialization's performance problems. Externalizable objects do not have their superclass state serialized, even if the superclass is Serializable. This can be used to cafe cover letter, reduce the data written out during serialization. Use Serializable by default, then make classes Externalizable on research on religion and science a case-by-case basis to improve performance. Web application scalability. (Page last updated June 2000, Added 2001-05-21, Author Billie Shea, Publisher STQE Magazine). Tips: Web application scalability is the ability to sustain the required number of simultaneous users and/or transactions, while maintaining adequate response times to end users. Letter. The first solution built with new skills and new technologies will always have room for improvement. Avoid deploying an application server that will cause embarrassment, or that could weaken customer confidence and business reputation [because of bad response times or lack of essay, calability]. Letter. Consider application performance throughout each phase of development and into production.
Performance testing must be an integral part of on wilderness, designing, building, and cafe cover maintaining Web applications. There appears to essays on wilderness, be a strong correlation between the use of performance testing tools and cafe cover the likelihood that a site would scale as required. Clinical Support System Case. Automated performance tests must be planned for and iteratively implemented to identify and remove bottlenecks. Cafe Cover Letter. Validate the architecture: decide on research on religion the maximum scaling requirements and then performance test to cafe, validate the necessary performance is achievable. This testing should be done on the prototype, before the application is built. Have a clear understanding of how easily your configurations of Web, application, and/or database servers can be expanded.
Factor in research paper on religion and science, load-balancing software and/or hardware in order to efficiently route requests to the least busy resource. Consider the effects security will have on performance: adding a security layer to transactions will impact response times. Dedicate specific server(s) to handle secure transactions. Select performance benchmarks and use them to quantify the scalability and determine performance targets and future performance improvements or degradations. Include all user types such as information-gathering visitors or transaction visitors in your benchmarks. Perform Performance Regression Testing: continuously re-test and measure against the established benchmark tests to ensure that application performance hasn?t been degraded because of the changes you?ve made.
Performance testing must continue even after the application is deployed. For applications expected to perform 24/7 inconsequential issues like database logging can degrade performance. Continuous monitoring is letter, key to spotting even the support case, slightest abnormality: set performance capacity thresholds and monitor them. Cafe Letter. When application transaction volumes reach 40% of maximum expected volumes, it is time to start executing plans to expand the research paper and science, system. Web Load Test Planning (Page last updated April 2001, Added 2001-05-21, Author Alberto Savoia, Publisher STQE Magazine). Tips: The only reliable way to determine a system?s scalability is to perform a load test in which the letter, volume and on technology and fitness characteristics of the anticipated traffic are simulated as realistically as possible. It is hard to design and develop load tests that come close to matching real loads. Characterize the anticipated load as objectively and cafe cover systematically as possible: use existing log files where possible; characterize user sessions (pages viewed - number and types; duration of session; etc). Determine the range and distribution of i did break, variations in cafe cover, sessions. Don't use averages, use representative profiles. Estimate target load and peak levels: estimate overall and what i did on spring break peak loads for letter, the server and expected growth rates.
Estimate how quickly target peaks levels will be reached, and for how long they will be sustained. The duration of the peak is important and the server must be designed to essay more to the lake, handle it. The key elements of a load test design are: test objective (e.g. Cover. can the essay, server handle N sessions/hr peak load level?); pass/fail criteria (e.g. Cafe. pass if response times stay within define values); script description (e.g. Essay And Fitness. user1: page1, page2, . ; user2: page1, page3, start transaction1, etc); scenario description (which scripts at which frequency, and how load increases). Performance chapter (chapter 20) from Professional JSP 2nd Edition (Page last updated August 2001, Added 2001-10-22, Author Simon Brown, Robert Burdick, Darko Cokor, Jayson Falkner, Ben Galbraith, RodJohnson, Larry Kim, Casey Kochmer, Thor Kristmundsson, Sing Li, Dan Malks, Mark Nelson, Grant Palmer, Bob Sullivan, Geoff Taylor, John Timney, Sameer Tyagi, Geert Van Damme, Steve Wilkinson, Publisher The Server Side). Tips: The user's view of the cafe cover, response time for research on religion, a page view in his browser depends on download speed and on the complexity of the page. e.g. the number of graphics. Cafe Cover. A poorly-designed highly graphical dynamic website could be seen as 'slow' even if the what on spring break essay, web downloads are individually quite fast. No web application can handle an unlimited number of requests; the cafe cover, trick in what i did on spring essay, optimization is to anticipate the likely user demand and ensure that the cafe, web site can gracefully scale up to the demand while maintaining acceptable levels of speed. Clinical Decision Support System Case. Profile the letter, server to identify the cause computer, bottlenecks. Note that profiling can be done by instrumenting the code with measurement calls if a profiler is unavailable. One stress test methodology is: determine the cafe cover letter, maximum acceptable response time for getting a page; estimate the maximum number of simultaneous users; simulate user requests, gradually adding simulated users until the essay and fitness, web application response delay becomes greater than the letter, acceptable response time; optimize until you reach the desired number of users. Pay special attention to research paper, refused connections during your stress test: these indicate the cafe cover, servlet is overwhelmed.
There is little performance penalty to using an MVC architecture. Use resource pools for essay in younger generation, expensive resources (like database connections). Static pages are much faster than dynamic pages, where the web server handles static pages separately. Servlet filtering has a performance cost. Test to see if it is an acceptable cost.
Ensure that the webserver is configured to letter, handle the expected number of user for example: enough ready sockets; enough disk space; enough CPU. Use the fastest JVM you have access to. Chapter 3 of and fitness generation, High Performance Java Computing : Multi-Threaded and cafe Networked Programming, Race Conditions and Mutual Exclusion (Page last updated January 2001, Added 2001-02-21, Authors George Thiruvathukal, Thomas Christopher, Publisher Sun). Tips: Execute I/O in blocks rather than one byte at essay on technology and fitness a time. I/O reads are normally faster than writes. Cafe Cover Letter. This means that I/O performance can be improved by research paper, decoupling reading and writing to dedicated threads, rather than interleaving reads and writes.
NOTE THE TIP volatile primitive datatypes have atomic ++ operations HAS BEEN SHOWN TO BE INVALID [The chapter describes implementations for lock objects (wait until unlocked), counting semaphore objects (wait until positive), barrier sempahore objects (wait until last thread is finished), future objects (wait until a variable is first set). These do not directly improve performance, but provide useful techniques for synchronizing threads that assist a multi-threaded program in being efficient]. Use resource enumeration (acquire resources in cafe, a set order) to avoid deadlocks. Chapter 4 of High Performance Java Computing : Multi-Threaded and once more Networked Programming, Monitors (Page last updated January 2001, Added 2001-02-21, Authors George Thiruvathukal, Thomas Christopher, Publisher Sun). Tips: Java monitors are not necessarily the most efficient synchronization mechanism, especially if transferring the lock can lead to cafe cover letter, a race condition [chapter discusses a more complete Monitor class]. volatile fields can be slower than non- volatile fields, because the system is forced to store to memory rather than use registers. Decision. But they may useful to avoid concurrency problems. [The chapter discusses various policies for synchronizing threads trying to read from or write to shared resources, which provide different scheduling policies: one thread at a time; readers-preferred (readers have priority); writers-preferred (writers have priority); alternating readers-writers (alternates between a single writer and a batch of cover letter, readers); take-a-number (first-come, first-served)]. Benchmarking JMS (Page last updated March 2001, Added 2001-03-21, Author Dave Chappell, Bill Wood, Publisher Java Developers Journal). Tips: Scaling middleware exposes a number of essay on technology, issues such as threading contention, network bottlenecks, message persistence issues, memory leaks, and overuse of object allocations. [Article dicusses questions to ask when setting up benchmarks for messaging middleware]. Message traffic under high-volume conditions are unpredictable and bursty. Messages can be produced far faster than they can be consumed, causing congestion.
This condition requires the message sends to be throttled with flow control (could be an exception, or an automatic resend). When testing performance, run overnight and over weekends to generate longer term trends. Some concerns are: testing without a real network connection can give false measures; low user simulation can be markedly different from high user simulations; network throughput may be large than the deployed environment; nonpersistent message performance is dependent on processor and memory; disk speed is crucial for persistent messages. [Article provides a benchmark harness for testing JMS]. Designing Java Performance: reducing object creation (Page last updated March 2001, Added 2001-03-21, Author Brian Goetz, Publisher JavaWorld). Tips: Watch out for method interfaces which force unnecessary or inefficient object creation. Cafe. Immutable objects are inefficient if you want to alter their structure, but efficient for sharing.
One way to cause effect, avoid creating objects simply for information is to provide finer-grained methods which return information as primitives. This swaps object creation for increased method calls. Cafe. A second technique to avoid creating objects is to provide methods which accept dummy information objects that have their state overwritten to pass the eb white more, information. Cafe Letter. A third technique to more to the, avoid creating objects is to provide immutable classes with mutable subclasses, by having state defined as protected in cover letter, the superclass, but with no public updators. The subclass provides public updators, hence making it mutable. Don't try to speed up the application if there is no performance problem. Some performance tips (Page last updated January 2001, Added 2001-01-19, Author Shyam Lingegowda, Publisher The Server Side). Tips: Use buffering for files stream i/o . Use byte streams (not char-streams) for ASCII characters. Recycle objects wherever possible.
Factor out constant computations from loops. For Servlets, push one time computations into the init() method. Decision System Case. Use StringBuffer when dealing with mutable strings. Cover. Initialize the StringBuffer with proper size. I Did On Spring. Let the compiler do compile time string concatenation.
Comparison of two string objects is faster if they differ in length. Cover. StringTokenizer is clinical decision support, slow. minimize the number of objects you create. Avoid initializing twice. Order boolean expressions so that they execute as fast as possible. Cover Letter. ArrayList is essays on wilderness, faster than Vector.
Minimize calls to Date and related classes. Expiring cached data (Page last updated January 2001, Added 2002-01-25, Author William Grosso, Publisher OnJava). Tips: Caching data on the client can improve performance, reduce communication overheads and increase the scalability of an application. Be careful when caching information that the cache doesn't contain out-of-date or incorrect information. Cafe Cover. Servlet sessions expire after a settable timeout, but screens that automatically refresh can keep a session alive indefinitely, even when the once more lake, screen is no longer in use.
Database connection pools can take one of two strategies: a limited size pool, where attempts to make connections beyond the pool size must wait for a connection to become idle; or a flexible sized pool with a preferred size which removes idle connections as soon as the preferred size is cafe, exceeded (i.e. temporarily able to research paper on religion, exceed the preferred size). The fixed size pool is generally considered to be the cafe letter, better choice. A time-based expiration strategy is appropriate for essay generation, most types of cache elements. The timestamp strategy is: Timestamp the objects; Update the time stamp when you use the objects or refresh the information; Throw away objects whose timestamps have expired. Only data that must be always totally up to letter, date cannot effectively use a time-based expiration strategy. [Article discusses and implements a time-based expiration framework]. J2ME game building (Page last updated April 2002, Added 2002-05-19, Author Dale Crowley, Publisher DevX). Tips: J2ME device memory and speeds are very limited which affects everything from the data-loading speed to the frame/refresh rate, and clinical case study seriously limits the ability to animate characters or otherwise rapidly change the cafe letter, screen. Smart graphics is cause, important: you need to draw clear, concise images at extremely low resolutions and with very small palettes. Animated characters need dynamic, easily-read poses which avoid kicks looking like a dance steps, or punches looking like an arm waves.
Use public variables in your classes, rather than using accessors. Cover Letter. This is technically bad programming practice but it saves bytecode space. Be extra careful to place things in essay more lake, memory only when they are in use. For example, discard an introduction splash screen after display. Try to reduce the number of cover letter, classes used. Combine classes into one if they vary only slightly in on wilderness survival, behavior. Every class adds size overheads. Cafe Cover Letter. Remember that loading and installing applications into J2ME phones is what i did on spring break, a relatively slow process. Sun community chat on cover High Performance GUIs with the JFC/Swing, with Steve Wilson, Scott Violet, and Chet Haase (Page last updated April 2002, Added 2002-05-19, Author Edward Ort, Publisher Sun). Tips: [Some discussion of performance improvents in 1.4] Multi-threading with swing must be done correctly, using invokeAndWait() and invokeLater().
Default models have performance limitations. Create dedicated models for high performance. Consider using a custom RepaintManager for very large tables. Don't use a MouseListener with a renderer BufferedImage is cause effect essay addiction, treated more optimally than MemoryImageSource Try using createImage(w,h), which returns an image in the same format as the screen, which allows faster copies from that image to the screen (important for copying speed issues). LinkedHashMap and RandomAccess (Page last updated July 2002, Added 2002-07-24, Author Glen McCluskey, Publisher Sun). Tips: LinkedHashMap preserves various ordering information, optionally including access ordering which makes LinkedHashMap appropriate for a least recently used (LRU) cache. ArrayList has fast random access of letter, elements, LinkedList has slow random access of elements.
List classes that implement the RandomAccess interface have fast random access and using get() to iterate their elements is essay on technology and fitness in younger, efficient. If RandomAccess is cover letter, not implemented, use an Iterator to iterate the elements. Data expiration in effect addiction, caches (Page last updated January 2002, Added 2002-02-22, Author William Grosso, Publisher OnJava). Tips: [Article discusses and implements a framework for a cache with built in element expiration handling]. Emulating another system (a ZX Spectrum) (Page last updated July 2002, Added 2002-07-24, Author Razvan Surdulescu, Publisher Java Developers Journal).
Tips: Painting pixel by pixel by repeatedly calling fillRect() is slow. Instead create the offscreen image as a decorator for cover letter, a java.awt.image.MemoryImageSource object containing a byte array in i did on spring break, RGB format with the pixel data. The rendering code updates the byte array and then calls MemoryImage-Source.newPixels() to notify the object that the data has been updated. Pre-render common images or pixel combination, retain them as Image objects and use java.awt.Graphics.drawImage() (Java 1) or java.awt.image.BufferedImage.setRGB() (Java 2) to render the image to the graphics buffer. Report of how Ace's Hardware made their SPECmine tool blazingly fast (Page last updated December 2001, Added 2002-02-22, Author Chris Rijk, Publisher Ace's Hardware). Cafe Letter. Tips: Tranform your data to minimize the costs of searching it. If your dataset is paper and science, small enough, read it all into memory or use an in-memory database (keeping the primary copy on disk for cafe, recovery). On Spring Essay. An in-memory datavase avoids the following overheads: no need to cover letter, pass data in from a separate process; less memory allocation by avoiding all the data copies as it's passed between processes and layers; no need for data conversion; fine-tuned sorting and filtering possible; other optimizations become simpler. Pre-calculation makes some results faster by making the database data more efficient to access (by ordering it in advance for decision support case study, example), or by setting up extra data in advance, generated from the main data, to make calculating the results for a query simpler.
Pre-determine possible data values in queries, and use boolean arrays to access the chosen values. Pre-calculate all formatting that is invariant for cover letter, generated HTML pages. Cause Effect Essay Computer. Cache all reused HTML fragments. Cover. Caching many strings may consume too much memory. IF memory is limited, it may be more effective to generate strings as needed. Write out strings individually, rather than concatenating them and writing the result. Extract common strings into an identical string object.
Compress generated html pages to clinical decision support case study, send to cover, the user, if their browser supports compressed html. Research And Science. This is cafe cover, a heavier load on cause effect essay the server, but produces a significantly faster transfer for limited bandwidth clients. Cafe Cover Letter. Some pages are temporarily static. Cache these pages, and only re-generate them when they change. Caching can significantly improve the responsiveness of a website. Email summarizing best practices for clinical decision system study, Promoting Scalable Web Services (Page last updated January 2002, Added 2002-02-22, Author Roger L. Costello, Publisher Costello).
Tips: Web services best practices are mainly the same as guidelines for developing other distributed systems. Stay away from using XML messaging to do fine-grained RPC, e.g. a service that returns a single stock quote (amusingly this is the classic-cited example of a Web service). Do use course-grained RPC, that is, use Web services that do a lot of work, and return a lot of cover letter, information. When the transport may be slow and/or unreliable, or the processing is complex and/or long-running, consider an asynchronous messaging model. Always take the overall system performance into clinical decision support system case study account. Don't optimize until you know where the bottlenecks are, i.e., don't assume that XML's bloat or HTTP's limitations are a problem until they are demonstrated in your application. Cover. Take the frequency of the messaging into on technology generation account. Replicate data as necessary. For aggregation services, try to retrieve data during off-hours in large, course-grained transactions. Caching SOAP services (Page last updated March 2002, Added 2002-03-25, Author Ozakil Azim and Araf Karsh Hamid, Publisher JavaWorld). Tips: Repeated SOAP-client calls to access server state can choke a network and degrade the server performance.
Cache data on the client whenever possible to avoid requests to the server. Ensure the client data remains up to date by using a call to a server service which blocks until data is changed. String concatenation, and cafe cover IO performance. (Page last updated March 2002, Added 2002-03-25, Author Glen McCluskey, Publisher Sun). Cause Effect Essay Addiction. Tips: String concatenation '+' is letter, implemented by the Sun compiler using StringBuffer, but each concatenation creates a new StringBuffer so is inefficient for essay and fitness in younger, multiple concatenations. Immutable objects should cache their string value since it cannot change. Operating systems can keep files in cover letter, their own file cache in memory, and accessing such a memory-cached file is much faster than accessing from disk.
Be careful of this effect when making I/O measurements in effect essay addiction, performance tests. Fragmented files have a higher disk access overhead because each disk seek to find another file fragment takes 10-15 milliseconds. Keep files open if they need to be repeatedly accessed, rather than repeatedly opening and closing them. Use buffering when accessing file contents. Cover Letter. Explicit buffering (reading data into an array) gives you direct access to the array of data which lets you iterate over the elements more quickly than using a buffered wrapper class. Counting lines can be done faster using explicit buffering (rather than the readLine() method), but requires line-endings to be explicitly identified rather than relying on the library method determining line-endings system independently. Sun community chat on EJBs with Pravin Tulachan (Page last updated March 2002, Added 2002-03-25, Author Edward Ort, Publisher Sun). Tips: CMP (container managed persistence) is generally faster than BMP (bean managed persistence).
BMP can be faster with proprietary back-ends; with fine-grained transaction or security requirements; or to gain complete detailed persistency control. Scalability is improved by passing primary keys rather than passing the entities across the essays, network. EJB 2.0 CMP is far faster than EJB 1.1 CMP. EJB 1.1 CMP was not necessarily capable of scaling to high transaction volumes. If EJBs provide insufficient performance, session beans should be used in preference. Letter. Don't make fine-grained method calls across the network. Use value object and session facade design patterns instead. Multithreading and support system read-write locks (Page last updated January 2002, Added 2002-01-25, Author Nasir Khan, Publisher EarthWeb).
Tips: When a thread passes through a synchronized block, all variables throughout the thread are synchronized with main memory, not just the set of variables in the current method. Multithreading and read-write locks, part 2 (Page last updated January 2002, Added 2002-01-25, Author Nasir Khan, Publisher EarthWeb). Tips: Operations on primitive variables are atomic (except double and cafe cover long), but a combination of two atomic operations is not atomic, and it is on technology and fitness in younger, easy to letter, make a mistake about this. Volatile variables are always synchronized with the main memory copy. Hotspot garbage collection in detail (Page last updated January 2002, Added 2002-01-25, Author Ken Gottry, Publisher JavaWorld). Computer. Tips: HotSpot garbage collection default parameters are effective for most small applications, but can be tuned to improve throughput for large, server-side applications. The most straightforward garbage collection algorithms iterate over letter, every reachable object: this takes an amount of time proportional to clinical decision support system, the number of living objects.
Throughput (the percentage of total time not spent in GC) is cover, normally the relevant metric for i did break essay, a server process since GC pauses may be tolerable or simply obscured by network latency. Pauses (the times during GC when an application is unresponsive) is the more relevant metric for interactive graphical programs and other programs where short pauses may upset the user experience. On systems with limited physical memory, footprint (the working set of a process, usually measured in pages) may dictate scalability. [Article dicusses various parameters available to tuning HotSpot heap space]. Cover Letter. Use verbosegc to capture garbage collection statistics. Quality of service for web services (Page last updated January 2002, Added 2002-02-22, Author Anbazhagan Mani, Arun Nagarajan, Publisher IBM). Tips: Quality of service requirements for web services are: availability (is it running); accessiblity (can I run it now); integrity/reliability (will it crash while I run/how often); throughput (how many simultaneous requests can I run); latency (response time); regulatory (conformance to standards); security (confidentiality, authentication). HTTP is a best-effort delivery service. Effect Computer Addiction. This means any request could simply be dropped. Web services have to handle this and retry.
Web service latencies are measured in cover, the tens to thousands of milliseconds. Cause Effect Addiction. Asynchronous messaging can improve throughput, at the cost of latency. SOAP overheads include: extracting the SOAP envelope; parsing the contained XML information; XML data cannot be optimized very much; SOAP requires typing information in every SOAP message; binary data gets expanded (by an average of 5-fold) when included in XML, and also requires encoding/decoding. Most existing XML parsers support type checking and letter conversion, wellformedness checking, or ambiguity resolution, making them slower than optimal. Consider using of stripped down XML parser which only pe4rforms essential parsing. DOM based parsers are slower than SAX based ones. Compress the XML when the CPU overhead required for what, compression is less than the network latency.
Other factors affecting web service performance are: web server response time and availability; web application execution time (like EJB/Servlets in Web application server); back-end database or legacy system performance. Requests results should be cached where possible. Requests should be load balanced, prioritized according to the business value it represents. Carry out letter capacity planning to enable the performance to be maintained in the future. Extreme care should be taken to make sure that resources are not locked for long periods of time, to avoid serious scalability problems. What Break. Measure the cafe cover, performance of your web services by adding code measuring elapsed time to essays, the generated service proxy (and recompiling). [Article gives an cafe example]. Object Resource Pooling (Page last updated March 2002, Added 2002-03-25, Author Paul King, Publisher OCI). Tips: If the overhead associated with creating a sharable resource is expensive, that resource is on spring essay, a good candidate for pooling. Pooled objects create a resource in cafe letter, advance and research store it away so it can be reused over-and-over. Pooling may be necessary if a limited number of shared resources are available. Pooling supports strategies such as load balancing, all-resources-busy situations, and other policies to optimize resource utilization. [Article discusses pooling characteristics].
Load balancing is possible by varying how pooled objects are handed out. Pool size can be tuned using low-water and high-water marks. Waiting time when accessing empty pools can be tuned using a timeout parameter. Unusable pooled objects may be recovered when most efficient, not necessarily when the underlying resource fails. The Recycler pattern fixes only the cafe letter, broken parts of a failed object, to essays, minimize the replacement cost.
Using NIO (Page last updated March 2002, Added 2002-03-25, Author Aruna Kalagnanam and Balu G., Publisher IBM). Cafe Cover. Tips: A server that caters to hundreds of clients simultaneously must be able to use I/O services concurrently. Prior to study, 1.4, an almost one-to-one ratio of threads to cafe cover, clients made servers written in Java susceptible to enormous thread overhead, resulting in both performance problems and research and science lack of scalability. Cafe Letter. The Reactor design pattern demultiplexes events and dispatches them to registered object handlers. On Wilderness. (The Observer pattern is similar, but handles only a single source of events where the Reactor pattern handles multiple event sources). Cover Letter. [Articles covers the changes needed to use java.nio to make a server efficiently muliplex non-blocking I/O from once to the, SDK 1.4]. J2EE best practices. Letter. (Page last updated February 2002, Added 2002-03-25, Author Chris Peltz, Publisher HP). I Did Break. Tips: Executing a search against the database calls one of the cafe, finder() methods. finder() methods must return a collection of clinical decision, remote interfaces, not ValueObjects. Consequently the client would need to make a separate remote call for each remote interface received, to acquire data. The SessionFacade pattern suggests using a session bean to encapsulate the query and return a collection of ValueObjects, thus making the request a single transfer each way.
The Value Object Assembler pattern uses a Session EJB to aggregate all required data as various types of cafe cover letter, ValueObjects. This pattern is what i did on spring essay, used to satisfy one or more queries a client might need to execute in order to display multiple data types. MIDP GUI programming (Page last updated March 2002, Added 2002-03-25, Author Qusay Mahmoud, Publisher OnJava). Tips: Applications with high screen performance needs, like games, need finer control over MIDP screens and should use the javax.microedition.lcdui package which provides the cafe, low-level API for handling such cases. Research And Science. Always check the drawing area dimensions using Canvas.getHeight() and cover letter Canvas.getWidth() [so that you don't draw unnecessarily off screen]. Not all devices support color. What I Did Break. Use Display.isColor() and cafe letter Display.numColors( ) to determine color support and essay lake avoid color mapping [overheads].
Double buffering is possible by using an offscreen Image the size of the screen. Creating the image: i = Image.createImage(width, height); Getting the Graphics context for drawing: i.getGraphics(); Copying to the screen g.drawImage(i, 0, 0, 0); Check with Canvas.isDoubleBuffered(), and cafe cover letter don't double-buffer if the MIDP implementation already does it for what i did break essay, you. Cafe Cover. To avoid deadlock paint() should not synchronize on any object already locked when serviceRepaints() is called. Effect Essay. Entering alphanumeric data through a handheld device can be tedious. If possible, provide a list of letter, choices from which the clinical system case, user can select. Article on the cost of casts (Page last updated December 1999, Added 2000-12-20, Author Dennis M. Sosnoski, Publisher JavaWorld). Cafe Letter. Tips: Casting can be detrimental to performance. Improve performance by minimizing casting in heavily used code. Some casts take nearly as long as a simple object allocation. Essays On Wilderness. [Article discusses various ways of cover, avoiding casts, showing advantages and drawbacks.] Article on clinical decision support system case Java 2 collections (Page last updated , Added 2000-12-20, Author Dennis M. Sosnoski, Publisher JavaWorld). Tips: Convert collections into cover arrays for computer addiction, improved access speed.
The conversion can be made slightly faster by cafe cover letter, implementing it in a subclass so that collection element access can avoid access methods, accessing elements directly. Customized implementations of Hashtables can perform better. Use type specific implementations of collections for better performance (e.g. IntegerVector rather than Vector) [Article describes a type-generic base class for typed arrayed collections.] Scaling SOAP-based web services. (Page last updated November 2001, Added 2001-11-27, Author Frank Cohen, Publisher IBM). Tips: Cache the web services description language (WSDL) in a centralized database and periodically check for newer versions. Cache schema definitions for scalability. Use simple SOAP data types (String, Int, Float, NegativeInteger).
Each new data type introduces a serializer to convert from the XML value into a Java value and back again, which may cause performance problems. SOAP messages move much more data than the eb white once to the, average HTTP GET or POST call, adversely impacting network performance. Transactional SOAP calls need to cache the cover letter, state of sessions. [Article dicusses a free open-source utility called Load to stress test SOAP-based web services]. Rules and on religion Patterns for Session Facades (Page last updated June 2001, Added 2001-07-20, Author Kyle Brown, Publisher IBM). Tips: Use the Facade pattern, and specifically Value objects, to transfer all the subset of letter, data needed from an entity bean in one transfer. EJBs are wonderful (Page last updated December 2001, Added 2001-12-26, Author Tyler Jewell, Publisher OnJava). Tips: The out-of-the-box configuration for Entity EJB engines, such as WebLogic, are designed to handle read-write transactional data with the best possible performance. There are studies that demonstrate entity EJBs with CMP have lackluster performance when compared with a stateless session bean (SLSB) with JDBC. [Author points out however that SLSB/JDBC combination is less robust, less configurable, and less maintainable]. Configure separate deployments for each entity bean for different usage patterns (e.g. typical 85% read-only, 10% read-write, 5% batch update), and partition the presentation layer to essay on technology in younger, use the appropriate corresponding deployment (e.g. read requests use the read-only deployment).
EJB performance tips (Page last updated December 2001, Added 2001-12-26, Author Krishna Kothapalli and cafe cover letter Raghava Kothapalli, Publisher JavaPro). Tips: Design coarse-grained EJB remote interfaces to reduce the number of network calls required. Decision. Combine remote method calls into one call, and combine the data required for the calls into one transfer. Reduce the cafe cover, number of JNDI lookups: cache the home handles. Use session bean wrapper for returning multiple data rows from an entity bean, rather than returning one row at a time. Use session beans for database batch operations, entity beans typically operate only one row at a time. Use container-managed persistence (CMP) rather than bean-managed persistence (BMP). Use entity beans when only a few rows are required for the entity, and when rows need to be frequently updated. Use the on religion, lowest impact isolation (transaction) level consistent with maintaining data coherency. Highest impact down: TRANSACTION_SERIALIZABLE, TRANSACTION_REPEATABLE_READ, TRANSACTION_READ_COMMITED, TRANSACTION_READ_UNCOMMITED. Correctly simulate the production environment to tune the application, and use profiling and other monitroing tools to identify bottlenecks.
Tune the underlying system, e.g. TCP/IP parameters, file limits, connection pool parameters, EJB pools sizes, thread counts, number of JVMs, JVM heap size, shared pool sizes, buffer sizes, indexes, SQL queries, keep/alive parameters, connection backlogs. Cafe Letter. Use clustering to meet higher loads or consider upgrading the hardware. Both Java specific and Java on OS/390 tips. (Page last updated 2000, Added 2000-10-23, Author ?, Publisher IBM). Tips: Use the latest release of the SDK. Use zip and paper on religion jar files.
Partition classes to different zip/jar files according to usage. Order the entries in CLASSPATH so that classes are found quickly (the default classloaders do a linear search in each entry's directory or zip/jar file). If using a large number of threads (thousands) tune the underlying OS to support this. Vary the -ss parameter to optimize for cafe cover letter, threads. Threads generally don't need more than 256K stack size. Minimize the number of essay on technology in younger, JNI calls Use primitive types for variables Avoid excessive writing to the Java console Use synchronized methods only when necessary Cache/reuse frequently used objects when possible Declare methods as final [dubious tip].
Use static final when creating constants Use int instead of long. Use local variables in preference to class and instance variables. Use arrays instead of vectors Consider when to use a temporary variable to manipulate class and instance variables in cafe cover, loops (speed vs. memory) Add and delete items from the end of a vector Avoid unnecessary cast and on spring instanceof Avoid using String when doing a lot of cafe cover letter, character manipulation. Essays Survival. Use StringBuffer instead. Cafe Cover. Avoid using long divides. Javaworld tip article, detailing a buffered RandomAccessFile class. Essay On Technology In Younger Generation. (Page last updated 1998?, Added 2000-10-23, Author Nick Zhang). Unfortunately the getNextLine() is too system specific - don't forget systems where lines are 'r' terminated. Tips: Use buffered i/o classes. Re-implement classes to avoid synchronization, where this is cover, applicable. RMI performance tuning (Page last updated September 2001, Added 2001-10-22, Author Ashok Mathew and Mark Roulo, Publisher JavaWorld).
Tips: Use netperf to measure network bandwidth. Consider altering the TcpWindowSize parameter. On Wilderness Survival. Configure RMI garbage collection by setting the cafe cover, properties sun.rmi.dgc.client.gcInterval and sun.rmi.dgc.server.gcInterval . And Science. Send groups of cover letter, objects together rather than one object at a time. Implementing Externalize can speed up transfers. Essays On Wilderness Survival. Pack data to reduce the number and cover amount of reads and writes, and the amount of data transferred. Have object directly serialize contained objects or tell those objects to on spring, serialize themselves using Externalize methods (i.e. chain Externalize methods for all contained objects). Cafe. Use special codes to handle special cases such as singleton or reusable objects. Don't introduce extra complications once performance targets have been met.
Local entity beans (Page last updated October 2001, Added 2001-10-22, Author Alex Pestrikov, Publisher Java Developers Journal). Tips: Local entity beans do not need to cause effect essay computer addiction, be marshalled, and do not incur any marshalling overhead for cafe, method calls either: parameters are passed by reference. Local entity beans are an optimization for research on religion and science, beans which it is known will be on the same JVM with their callers. Facade objects (wrappers) allow local entity beans to be called remotely. Cafe Cover Letter. This pattern incurs very little overhead for remote calls, while at the same time optimizing local calls between local beans which can use local calls. Nice article on understanding bytecodes by Peter Haggar, Added 2000-10-23, Author of Practical Java. Explains why a synchronized method is faster than a functionally identical synchronized block. (Page last updated 2000, Added 2000-10-23, Author Peter Haggar, Publisher IBM).
Tips: Understanding bytecodes can help determine how to improve performance. It can also help you to to the, create smaller sized class files. Don't synchronize code unless synchronization is required. Cafe Cover Letter. Use synchronized methods rather than synchronized blocks where the code would be functionally identical. The -O option in SDK 1.2 does nothing. Use the -g:none option to make files class smaller [or use a better optimizing compiler] Move invariants out of loops. And Fitness. Apply simple optimizations like loop unrolling, algebraic simplification, and strength reduction by hand. Chapter 1 of Enterprise Java Performance, Performance in General. Cover. Includes the eb white once, infamous sentences It is likely that the code will not meet the cafe cover letter, performance requirements the once, very first time it runs.
Even if it does, it may be worthwhile to look for letter, some ways to improve it. NO NO NO! If the code meets the performance requirements, DON'T CHANGE IT. Next time guys, ask me to review your book before you publish. (Page last updated 2000, Added 2000-10-23, Authors Steven Halter Steven Munroe, Publisher Sun). Tips: The simplest code usually performs best. Consider performance requirements before coding. Write reasonable code without worrying too much about essay performance until later. Letter. If the design identifies a critical section of code, spend time considering that code's performance before and cause while writing it. Define performance requirements explicitly. Cover Letter. Redefine fuzzy requirements to be more explicit. Cause Effect Essay. The target machine affects performance requirements.
Use the cafe letter, simplest classes possible--but no simpler. [Don'cha just love it. And here I was using classes simpler than is possible. Gotta make 'em more complex now.] Don?t recalculate things that are constant in loops. Reuse objects where possible. Choose the more, correct collection for performance. Use the default Java data values where possible to avoid reassigning them. Use raw arrays in preference to collections. Performance fixing is iterative. Cover. Fixing one bottleneck often reveals another previously hidden one.
Keep performance in mind during the design phase. Avoid monopolizing shared resources. Design is important for any distributed parts of a distributed application. The real performance limitations are physical limitations: bandwidth, communication distance, access speed, unavoidable overheads, resource limitations, etc. Clinical Decision Study. JNI calls are not necessarily faster than using pure Java because of JNI overheads.
Schema mapping is cafe cover, complex. [Buy a product that does it for you.] Chapter 4 of Enterprise Java Performance, Local/Remote Issues. (Page last updated 2000, Added 2000-10-23, Authors Steven Halter Steven Munroe, Publisher Sun). Tips: RMI over computer addiction, IIOP has a higher overhead than plain RMI. Objects that can be configured to be local or remote at any time, provides the flexibility to optimize performance. Large grained remote calls [i.e. batched calls] perform better than small grained remote calls [lots of little calls]. Persistency adds overheads that make persistent objects slower. Instead of serializing the transitive closure (recursive traversal of all objects referenced), break up objects into smaller chunks. Use stubs, proxies and handles [essentially objects that indirectly refer to other objects] to break up serialization into smaller chunks. Unless the application is put together with care, the remote method call costs may dominate. Group objects that interact strongly [a lot] in the same physical location.
The closer they are, the more efficient their interaction. Cache in the client any read-only objects, for letter, the whole session. Replicate any data needed so that queries run locally in the client. Written objects can be held in the client and periodically written to the server, rather than updating the server object on each change. Good partitioning of essay on technology and fitness in younger, objects in cafe cover, distributed applications limits interactions between objects in different partitions and takes advantage of local method access for objects within each partition.
Application partitioning is best addressed early in on technology in younger generation, the design. How to use java.rmi.MarshalledObject (Page last updated March 2001, Added 2001-04-20, Author Stuart Halloway, Publisher Sun). Cafe Letter. Tips: MarshalledObject lets you postpone deserializing objects. This lets you pass an object through multiple serialization/deserialization layers (e.g. passing an object through many JVMs), without incurring the on wilderness, serialization/deserialization overheads until absolutely necessary. Doug Bell's article with various low-level techniques and benchmark applets. (Page last updated 1997, Added 2000-10-23, Author Doug Bell, Publisher JavaWorld). Tips: Don't optimize unless necessary. Optimizing can: introduce new bugs; make code harder to understand and maintain; reduce the cafe cover letter, extensibility of the code. 90 percent of once, a program's excution time is letter, spent executing 10 percent of the code. (Some people use the cause essay, 80 percent/20 percent rule).
Optimizing the other 90 percent of the program (where 10 percent of the execution time was spent) has no noticeable effect on performance. General optimization techniques include: strength reduction; common sub expression elimination; code motion; unrolling loops. Use compiler features: constant folding; branch folding; dead code elimination. Use the cover, -O option (javac -O). Use a profiler to identify bottlenecks. Always time the code before and after making changes to verify that, at least on the test platform, your changes improved the program.
Try to make each timing test under identical conditions. If possible, contrive a test that doesn't rely on any user input, as the variations in i did on spring break, user response can cause the results to cafe, fluctuate. Tuning the IBM JVM and Linux (Page last updated May 2001, Added 2001-10-22, Authors Duc Vianney and James Phelan, Publisher IBM). Tips: [Article also has detailed coverage of tuning Linux]. Use the -Xms and -Xmx parameters to set the paper and science, heap size. Use -verbosegc to cover letter, measure garbage collection statistics. Keep heap size smaller than physical memory. Keep heap size small enough that all other necessary processes also fit into physical memory. The IBM JVM has extra options to control JVM Focus initially on design, data structures, and essay lake algorithms. Do not rely on letter compile-time code optimization.
Understand runtime code optimization. Use StringBuffer, rather than String, for concatenation. Essays. Minimize the cost of object creation. Guard against unused objects. Minimize synchronization.
Use stack variables whenever possible. Use static, final, and private methods to allow inlining. Cover Letter. Initialize instance variables only essay on technology, once. Use primitive types for faster and smaller code. Do not use an cafe letter Enumeration or an Iterator to traverse a Vector. Use System.arraycopy for cause, copying arrays. Prefer an array to a Vector or ArrayList. Cover Letter. Reuse objects whenever possible.
Use lazy evaluation. Optimize source code by on spring break, hand. Compile to native code. Performance tuning embedded Java (Page last updated August 2001, Added 2001-08-20, Author Vincent Perrier, Publisher OnJava). Tips: All the following affect embedded Java performance: hardware processor selection; (real-time) operating system selection; supported Java APIs; application reliability and scalability; graphics support; and the ability to put the application code into ROM. Cafe Cover. Various approaches for boosting bytecode execution speed include: a JIT compiler (usually too big for cause effect essay, embedded systems); an ahead-of-time compiler (requires more ROM, may disallow or slowdown dynamically loaded classes); a dynamic adaptive compiler (half-way house between last two options); putting the Java application code into cafe ROM; rewriting the JVM interpretation loop in assembly; using a Java hardware accelerator. Use the lightweight graphical toolkit. To keep down the memory footprint, eliminate any classes that are not used (java -v lists all classes as they are loaded), and run in interpreted mode as much as possible. Benchmark results are not necessarily applicable to your application [article reviews the applicability of standard and proprietary benchmarks]. Caching (Page last updated July 2001, Added 2001-08-20, Author Jonathan Lurie, Publisher JavaWorld). Tips: Nice description of caching using a filing system analogy.
Nice introductory description of implementating caching, and on technology and fitness generation of managing caching overheads and element expiration. J2EE challenges (Page last updated June 2001, Added 2001-07-20, Author Chris Kampmeier, Publisher Java Developers Journal). Tips: Thoroughly test any framework in a production-like environment to ensure that stability and performance requirements are met. Each component should be thoroughly reviewed and tested for its performance and security characteristics. Cafe. Using the eb white essay, underlying EJB container to manage complex aspects such as transactions, security, and remote communication comes with the cafe cover, price of additional processing overhead. To ensure good performance use experienced J2EE builders and use proven design patterns.
Consider the impact of session size on performance. Eb White. Avoid the following common mistakes: Failure to close JDBC result sets, statements, and connections; Failure to cafe cover, remove unused stateful session beans; Failure to computer addiction, invalidate HttpSession. Performance test various options, for example, test both Type 2 and Type 4 JDBC drivers; Use a load-generation tool to simulate moderate loads; monitor the server to identify resource utlization. Perform code analysis and profiling. Performance requirements include: the cover, required response times for end users; the perceived steady state and peak user loads; the average and peak amount of data transferred per support Web request; the cafe letter, expected growth in user load over the next 12 months. Note that peak user loads are the number of concurrent sessions being managed by the application server, not the number of possible users using the system. Larger loads require greater amounts of hardware to satisfy that load. Applications that perform very little work can typically handle many users for a given amount of essays on wilderness survival, hardware, but can scale poorly as they spend a large percentage of time waiting for shared resources. Applications that perform a great number of computations tend to require much more hardware per user, but can scale much better than those performing a small number of computations.
Processor integer performance is usually the most important hardware factor, though a server can scale poorly if shared resources cause significant contention. Cache design and cover letter memory bandwidth play a big role in determining how much extra performance is achieved, as processors are added to a server. Additional capacity should be designed into essay once the system. Cover. Extrapolate from cause essay computer, known performance test results to cover letter, predict the performance of the system when varying amount of resources are available. EJB Clustering (Page last updated February 2002, Added 2002-04-26, Author Tyler Jewell, Publisher BEA).
Tips: Four locations that can provide clustering logic for an EJB are: the JNDI naming server where the home stub is research, bound, the letter, container, the home stub, and the remote stub. J2EE Application servers (Page last updated April 2001, Added 2001-04-20, Authors Christopher G. Chelliah and Sudhakar Ramakrishnan, Publisher Java Developers Journal). And Fitness. Tips: A scalable server application probably needs to be balanced across multiple JVMs (possibly pseudo-JVMs, i.e. multiple logical JVMs running in the same process). Performance of an application server hinges on caching, load balancing, fault tolerance, and clustering. Cover Letter. Application server caching should include web-page caches and data access caches. Other caches include caching servers which guard the and fitness in younger generation, application server, intercepting requests and cafe cover letter either returning those that do not need to go to the server, or rejecting or delaying those that may overload the app server. Application servers should use connection pooling and database caching to minimize connection overheads and round-trips. Load balancing mechanisms include: round-robin DNS (alternating different IP-addresses assigned to on technology in younger generation, a server name); and re-routing mechanisms to distribute requests across multiple servers. Cover Letter. By maintaining multiple re-routing servers and a client connection mechanism that automatically checks for an available re-routing server, fault tolerance is decision system, added. Using one thread per user can become a bottleneck if there are a large number of concurrent users. Distributed components should consider the proximity of components to cafe letter, their data (i.e., avoid network round-trips) and how to distribute any resource bottlenecks (i.e., CPU, memory, I/O) across the different nodes.
Hans Bergsten's top ten JSP tips (Page last updated November 2000, Added 2001-01-19, Author Hans Bergsten, Publisher O'Reilly). Tips: The include directive (%@ include file=filename.inc %) is faster than the include action (jsp:include page=pagename.jsp flush=true/). redirect s are slower than forward s because the browser has to make a new request. Database access is typically very expensive in terms of server resources. Use a connection pool to share database connections efficiently between all requests, but don't use the JDBC ResultSet object itself as the cache object. The Optimistic Locking pattern (Page last updated July 2001, Added 2001-07-20, Author Yasmin Akbar-Husain and research paper Eoin Lane, Publisher JavaWorld).
Tips: Pessimistic locking, where database data is locked when read, can lead to high lock contention. Optimistic locking only checks data integrity at update time, so has no lock contention [but can have high rollback costs]. This is Optimistic Locking pattern is usually more scalable than pessimistic locking. Detection of write-write conflicts with optimistic transactions can be done using timestamps or version counts or state comparisons. Reusing objects in embedded Java (Page last updated July 2001, Added 2001-07-20, Author Angus Muir and Roman Bialach, Publisher Micro Java). Letter. Tips: A lot of object creation and destruction can lead to cause, a fragmented heap, which reduces the ability to create further objects.
Define the bulk of memory you need (buffers, etc.) up-front at initialization, and cafe use object pooling to avoid further creation or destruction of objects. Throwing/catching exceptions are tremendously expensive. Pooling is not always faster than object creation. Object recycling part 2 (Page last updated February 2002, Added 2002-02-22, Author Angus Muir and Roman Bialach, Publisher Micro Java). Tips: The efficiency of pooling objects compared to creating and disposing of objects is highly dependent on the size and complexity of the objects. Object pools have deterministic access and reclamation costs for both CPU and memory, whereas object creation and garbage collection can be less deterministic. Chapter 2, Java: Fat and Slow?, of in younger generation, Java 2 Micro Edition: Professional Developer's Guide referenced from http://www.microjava.com/articles/techtalk/giguere(Page last updated May 2001, Added 2001-07-20, Author Eric Giguere, Publisher Micro Java). Tips: Reduce compiled code size by using implicit instruction bytcodes wherever possible.
For example, limiting a method to four or fewer local variables (three on cafe cover letter non-static methods as this takes the first slot), allows the compiler to use implicit forms of instructions (such as aload, iload, fload, astore, istore, fstore, and so on). Research. Similarly numbers -1, 0, 1, 2, 3, 4 ,5 have special bytecodes Java class files are standalone - no data is shared between class files. In particular strings are repeated across different files (one reason why they compress so well when packaged together in JAR files). An empty class compiles to about 200 bytes, of which only cafe, 5 bytes are bytecode. There are no instructions for initializing complete arrays in the Java VM. Instead, compilers must generate a series of bytecodes that initialize the array element by element. This can make array initialization slow, and adds bytecode to the class. You can reduce bytecode bloat from decision support case study, array initialization by cafe, encoded values in strings and on spring break essay using those strings initialize the arrays.
Explicitly set references to null when they are no longer needed to letter, ensure that the objects can be garbage collected. Allocate objects less often and allocate smaller objects to reduce garbage collection frequency. Animation in java applets article. Old article, but basically sound (the basics haven't changed). (Page last updated March 1996, Added 2000-12-20, Authors Arthur van Hoff and Kathy Walrath, Publisher JavaWorld). Tips: Use a separate thread to draw the animation. Do not use the to the lake, paint() method. Letter. Destroy the animation drawing thread when the user leaves the page (Applet.stop() is called) to avoid consuming CPU when nothing is being viewed. Keep the correct frame rate by calculating elapsed time and delaying for the remaining time, rather than always simply delaying for a contant time period.
Override the essays on wilderness survival, update() method to avoid flashing (update() clears the frame each time it is painted). Use double buffering to eliminate further flashing and cafe letter usually faster drawing: drawing offscreen is potentially faster, and mapping blocks of survival, pixels oto the screen is normally very fast. Use a media tracker class to avoid displaying images until they are fully loaded. [This still applies, but Java 2 has more interfaces to help you do this.] Use image strips to load multiple images in one action. Inter-frame compression can reduce the cafe letter, total size of multiple images of an animation, and so improve animation network/disk transfer rates. Another tutorial from Sun. This ones on essay on technology and fitness in younger animation (Page last updated ?, Added 2000-12-20, Author ?, Publisher Sun). Cafe Letter. Tips: Normal frame rates for animation: 8 frames per second (fps) for poor quality animation; 12 fps for standard animation; 24 fps for short bursts of on technology in younger generation, smooth, realistic motion. Cafe Letter. Animation loop (usually a separate thread) keeps track of frames and requests screen updates. Suspend the animation whenever it is not visible. Use the MediaTracker to load all required images before drawing, using checkID(anInt, true)/checkAll(true) [asynchronously] or waitForID()/waitForAll() [synchronous]. [example code included in article] Combine images in a single file (e.g. jar file, or single image strip) to improve image loading if transferring them over a network. Basic animation tutorial (Page last updated ?, Added 2000-12-20, Author Dave ?, Publisher ?).
Tips: Avoid flicker by eb white essay to the lake, overriding the update() method to avoid blanking the canvas. Use a separate thread to letter, manage the calculations and drawing. Use MediaTracker to load all required images before drawing. What I Did. Use double buffering (draw image on cafe letter offscreen buffer, then map onto screen buffer). Clinical Decision System Case Study. Use synchronization to synchronize methods in the two threads. Moving from JSP to cafe, EJB (Page last updated June 2001, Added 2001-06-18, Author Patrick Sean Neville, Publisher Java Developers Journal). On Spring Break. Tips: Entity EJBs should contain aggregate get/set methods that return chunks of data rather than fine-grained get/set methods for individual attributes, to reduce unnecessary database, transactional, and network communication overheads. Avoid stateful session beans as they are resource-heavy, since one instance is maintained for each client. Under heavy loads, entity beans should do more than merely represent a table in a database.
If you are merely retrieving and updating data values, consider using JDBC within session beans instead. Cafe Cover Letter. If you have one large database host but only once, a small Web and middleware host, consider moving much of your logic into stored procedures and calling them via JDBC in session beans. If your database host is weak or unknown, or you require greater portability, keep the data calculations in entity beans. Cafe Cover. Consider using a single stateless session bean to on technology and fitness, provide access to other EJBs (this is a fa?ade pattern). This optimizes multiple EJB references and calls by letter, keeping them in-process. Container Managed Persistence (CMP) typically provides better performance (due to data caching) than Bean Managed Persistence (BMP). Judging various aspects of clinical system study, Java, including performance (Page last updated May 2001, Added 2001-06-18, Author Brian Maso, Publisher DevX). Tips: J2EE defines component models with high scalability potential.
Maximizing scalability requires sticking to letter, stateless session beans and handling all database interactions programmatically (through pooled JDBC connections). Decision Support System. EJBs are slower and more complex than proprietary server implementations when high scalability is not needed. Java (to 1.3) does not have non-blocking I/O, which virtually guarantees Java server implementations bind one thread per client connection. Cafe. This limits communication throughput. Some Java application servers provide proprietary non-blocking I/O to improve throughput. From the 1.4 SDK, Java includes non-blocking I/O. Using java.lang.reflect.Proxy (Page last updated July 2001, Added 2001-07-20, Author Tom Harpin, Publisher Sun). Research On Religion. Tips: Interposing proxy objects is a useful approach to trace or profile method calls. The java.lang.reflect.Proxy class allows you to create a wrapper around any object which implements an interface. Appendix A (Garbage Collection) of cafe letter, Java Platform Performance: Strategies and Tactics. Eb White Essay Once To The Lake. (Page last updated 2001, Added 2001-04-20, Authors Steve Wilson, Jeff Kesselman, Publisher Sun). Cafe. Tips: Large RAM requirements can force the OS to use virtual memory, which slows down the application.
Most JVM implementations will not dereference temporary objects until the method has gone out of scope, even if the object is created in an inner block which has gone out of scope. What Break. So you need to cafe cover letter, explicitly null the variable if you want it collectable earlier. Adding a finalizer method extends the life of the object, since it cannot be collected until the finalize() method is clinical decision system, run. Do not use finalizers to free resources in a timely manner. Various performance tips from a JavaOne 1998 presentation. (Page last updated September 1998, Added 2000-12-20, Author Tony Squier Steven Meloan, Publisher Sun). Tips: Minimize the number of cafe letter, times that an applet has to computer, request data from the server. Package Applet images into a single class file.
Use Thread pools where these improve performance. Use BufferedIO streams to access URLConnection's Input/Output streams. Load Balancing Web Applications (Page last updated September 2001, Added 2001-10-22, Author Vivek Veek, Publisher OnJava). Tips: DNS round-robin sends each subsequent DNS lookup request to the next entry for cafe cover, that server name. This provides a simple machine-level load-balancing mechanism, but is only appropriate for clinical system case, session independent or shared-session servers. DNS round-robin has no server load measuring mechanisms, so requests can still go to overloaded servers, i.e. the load balancing can be very unbalanced. Hardware load-balancers solve many of the letter, problems of DNS round-robin, but introduce a single point of failure. A web server proxy can also provide load-balancing by redirecting requests to multiple backend webservers. Article on computer addiction using CachedRowSet, a ResultSet that doesn't need continuous connection to the database (Page last updated February 2001, Added 2001-02-21, Author Taylor G. Cowan, Publisher JavaWorld).
Tips: CachedRowSet provides cached result sets that do not require continuous connection to the database, allowing connections to cover, be reused more efficiently. Using CachedRowSet lets you batch updates, and i did execute them asynchronously. CachedRowSet also supports offline work which is later synchronized. CachedRowSet is probably not appropriate for managing large datasets. JMS vs RMI (Page last updated February 2002, Added 2002-02-22, Author Kevin Jones, Publisher DevX). Tips: RMI calls marshall and demarshall parameters, adding major overhead.
Every network communication has several overheads: the distance between the sender and the receiver adds a minimum latency (limited by cover, the speed the essay in younger, signal can travel along the wire, about two-thirds of the speed of light: London to New York would take about cafe letter 3 milliseconds); each network router and switch adds time to respond to i did on spring break essay, data, on cafe cover the order of 0.1 milliseconds per device per packet. Clinical Decision Support System. Part of most network communications consists of small control packets, adding significant overhead. One RMI call does not generally cause a noticeable delay, but even tens of RMI calls can be noticeable to the users. Beans written with many getXXX() and setXXX() methods can incur an RMI round trip for cafe, every data attribute. Messaging is naturally asynchronous, and allows an application to on wilderness, decouple network communications from ongoing processing, potentially avoiding threads from being blocked on communications. Proxy code generation (Page last updated February 2002, Added 2002-02-22, Author Paul McLachlan, Publisher Java Developers Journal). Tips: Generative programming is a class of techniques that allows for more flexible designs without the performance overhead often encountered when following a more traditional programming style. Cafe Letter. JSP engines are one example. java.lang.reflect.Proxy is another. More advanced code obfuscations (such as control-flow obfuscation) can produce slower programs as the obfuscated bytecode is once to the, more difficult to optimize by the JIT or HotSpot compiler. Letter. A reflective lookup [obtaining the method reference from research paper on religion, its name] is cover letter, much slower than a reflective invoke [invoking the method from the reference] once you have a method reference. [Article provides an implementation of the JNI call using the JVM_OnLoad() function to essay, trap class bytecodes as they are loaded].
A generated Proxy class uses the Reflection API to look up the interface methods once in cover letter, its static initializer, and generates wrappers and access methods to handle passing primitive data between methods. [This means that a generated Proxy class will have a certain amount of effect essay, overhead compared to cover letter, the equivalent coded file]. Finalizers (Page last updated March 2002, Added 2002-04-26, Author Phil Vickers, Publisher IBM). Tips: Adding finalizers to your code makes GC much more expensive and cause essay addiction unpredictable. Finalizers are not executed at a predictable time. Sun community chat session: Tuning the cafe cover, Java Runtime for decision system, Big Iron (Page last updated March 2001, Added 2001-04-20, Author Edward Ort, Publisher Sun). Cover. Tips: Use the -server option. Use -XX:+UseLWPSynchronization (better threading) or on Solaris set LD_LIBRARY_PATH=/usr/lib/lwp:/usr/lib (even better threading). Paper On Religion. Set the young generation space to cafe letter, 1/4 to 1/3 of heap space, e.g. What On Spring. -Xms1024m -Xmx1024m -XX:NewSize=256m -XX:MaxNewSize=256m. On Solaris use vmstat, pstat (utilities) and -verbose:gc (runtime option). GC is single-threaded (at least to 1.3.x), so cannot take advantage of multiple-CPUs (i.e. can end up with multi-processor mostly idle during GC phases if using a single JVM).
Too many threads can lead to thread starvation [presumably thrashing]. Cover. Use at least one thread per CPU, more if any threads will be i/o blocked. On Solaris use the mpstat utility to monitor CPU utlization. 1.4 will include concurrent GC that should avoid large GC pauses. The biggest performance problem is bad design. Use: -XX:NewSize=value -XX:MaxNewSize=value rather than -XX:SurvivorRatio and cause essay -XX:NewRatio. Cafe Letter. Set initial heap size to eb white more to the, max heap size when you know what size heap you'll want and you want to avoid wasting time growing the heap as you'll fill up space. If you're not sure how big you'll want your heap to be you might want to set a smaller initial size and only grow to use the space if you need it. Low CPU utilization together with bad performance may indicate GC, synchronization, I/O or network inefficiencies. Cover Letter. -XX:MaxPermSize affects Perm Space size (storage for HotSpot internal data structures), and only needs altering if a really large number of classes are being loaded. [The session also discussed some Solaris OS parameters to tune]. For JDK 1.3, the heap is: TotalHeapSize = -Xmx setting + MaxPermSize; with -Xmx split into new and old spaces [i.e. total heap space is old space + new space + perm space, and settable heap using -Xmx defines the size of the old+new space. -XX:MaxNewSize defines how much of effect computer addiction, -Xmx heap space goes to new space].
Looks at Bluestone Total-e-server, Sybase Enterprise Application Server, SilverStream Application Server, and WebLogic Application Server. On Wilderness Survival. (Page last updated February 2001, Added 2001-03-21, Author Abraham Kang, Publisher JavaWorld). Tips: A cluster in this context is a group of machines working together to transparently provide enterprise services. A cluster can be implemented using a dispatcher which accepts requests and passes them on to other servers (either by redirecting the client or directly). Letter. Clusters target to provide scalability and high-availability. J2EE application servers implement clustering around their implementation of JNDI.
Clustering should allow failover if a machine/process crashes. For stateful sessions, this requires state replication. Database and once more filesystem session persistence can limit scalability when storing large or numerous objects in the HttpSession. To scale the static portions of your Website, add Web servers; to cafe, scale the clinical support, dynamic portions of your site, add application servers. Multicasting efficiency (Page last updated January 2002, Added 2002-02-22, Author Paul Timberlake, Publisher Message MQ).
Tips: When dealing with large numbers of active listeners, multicast publish/subscribe is more efficient than broadcast or multiple individual connections (unicast). When dealing with large numbers of listeners with only a few active, or if dealing with only a few listeners, multicasting is inefficient. This scenario is common in enterprise application integration (EAI) systems. Inactive listeners require all missed messages to be resent to them in order when the cover, listener becomes active. A unicast-based message transport, such as message queuing organized into a hub-and-spoke model, is more efficient than multicast for most application integration (EAI) scenarios. NIO (Page last updated Daniel F. Savarese, Added 2002-02-22, Author February 2002, Publisher JavaPro). Tips: GatheringByteChannel lets you to write a sequence of cause essay computer, bytes from multiple buffers, and ScatteringByteChannel allows you to read a sequence of cafe cover letter, bytes into multiple buffers. Clinical Decision Study. Both let you minimize the number of system calls meade by combining operations that might otherwise require multiple system calls.
Selector allows you to multiplex I/O channels, reducing the cover letter, number of threads required for efficient concurrent I/O operations. FileChannels allow files to be memory mapped, rather than reading into a buffer. This can be more efficient. [But note that both operations bring the file into memory in different ways, so which is faster will be system and data dependent]. Optimizing Searches via Rare Events (Page last updated April 2002, Added 2002-05-19, Authors ANDREA MONTANARI RICCARDO ZECCHINA, Publisher Nature). Tips: Re-starting a search algorithm at random times can improve the average time required to eb white more to the lake, reach the solution. Compression in letter, Java (Page last updated February 2002, Added 2002-02-22, Author Qusay H. Mahmoud and and science Konstantin Kladko, Publisher Sun). Cafe Cover Letter. Tips: Compression techniques have efficiencies that vary depending on the data being compressed. It's possible a proprietary compression technique could the most efficient for a particular application. For example, instead of transmitting a compressed picture, the i did on spring essay, component objects that describe how to draw the cafe letter, picture may be a much smaller amount of data to essay on technology in younger generation, transfer.
ZIPOutputStream and GZIPOutputStream use internal buffer sizes of 512. BufferedOutputStream is unnecessary unless the size of the buffer is significantly larger. GZIPOutputStream has a constructor which sets the internal buffer size. Zip entries are not cached when a file is read using ZipInputStream and letter FileInputStream, but using ZipFile does cache data, so creating more than one ZipFile object on decision system case study the same file only opens the cafe, file once. In UNIX, all zip files opened using ZipFile are memory mapped, and therefore the on technology and fitness generation, performance of ZipFile is superior to ZipInputStream. If the contents of the same zip file, are frequently changed then using ZipInputStream is cover, more optimal. Compressing data on the fly only improves performance when the data being compressed are more than a couple of hundred bytes. Porting to KVM (Page last updated February 2002, Added 2002-02-22, Author Shiuh-Lin Lee, Publisher Micro Java). Tips: Minimize program runtime size. Avoid third-party class libraries if not necessary, for example kAWT (a GUI toolkit library) and MathFP (Fixed point math).
Store big lookup tables in the user database rather than as part of the program. Call GC functions manually. Dispose of Objects; close the clinical study, database and the network connections as soon as they are no longer needed. Cover. Only load or transfer minimal required data structures and records into memory. Essay And Fitness. Avoid float and double calculations. Avoid data conversions: store and use the cover, data in the final required format, or execute conversions on the server. Clinical Decision Support Study. Use client caching. Data compression has to cover, be tuned to minimize both client CPU impact as well as transfer size. Use tabbed panels to hold different groups of information. Scrollable panel can have higher memory requirements than a tabbed panel. What I Did On Spring. Avoid some KVM user components (like ScrollTextBox), because they are runtime memory hogs.
Use selection lists rather than manual entry to speed up user data entry. Tracking Memory leaks (Page last updated February 2001, Added 2001-03-21, Author Jim Patrick, Publisher IBM). Tips: An object is only counted as being unused when it is no longer referenced. If objects remain referenced unintentionally, this is a memory leak. If you get a java.lang.OutOfMemoryError after a while, memory leakage is a strong suspect. If an application is meant to run 24 hours a day, then memory leaks become highly significant.
Most JVMs grow towards the upper heap limit (-Xmx/-mx options) when more memory is required, and do not return memory to the operating system, even if the memory is no longer needed, until the JVM process terminates. [Article provides an example of tracking memory leaks using JProbe]. BigDecimal and cafe letter Enumerations (Page last updated August 2001, Added 2001-08-20, Author Glen McCluskey, Publisher Sun). Tips: BigDecimal provides arbitrary-precision floating point number arithmetic, at the cost of performance. Type-safe enumeration is safer than using ints for enum values, and you can still use comparison by identity for fast performance. But you lose the performance potential of using the i did, enum values directly as array indices, switch constants and bitmasks. Article on connection pools (Page last updated September 1999, Added 2001-02-21, Author Hans Bergsten, Publisher Web Developers Journal). Tips: Reuse database connections using a connection pool.
Put helper classes (non-servlet classes used by cafe, servlets) in the CLASSPATH of the servlet engine. Weblogic's RMI framework (Page last updated January 1999, Added 2001-03-21, Author , Publisher BEA). Tips: Use a single, multiplexed, asynchronous, bidirectional connection for RMI client-to-network traffic instead of the standard reference implementation using multiple sockets. Try to essays survival, improve the serialization mechanism for faster RMI [Externalization is better]. Use local calls for objects located in the same JVM. Minimize distributed garbage collection. Use smart stubs which provide data caching and localized execution in cafe cover letter, addition to the normal remote execution and data fetching capabilities. Using VolatileImage (Page last updated May 2001, Added 2001-07-20, Author [email protected], Publisher Sun). Tips: Graphics performance in system case, 1.2 is worse than 1.1. Cover Letter. 1.3 is better, and on technology 1.4 should be the cafe cover letter, fastest yet.
From 1.2 direct access to essay addiction, image pixels was available, but was too slow to cafe cover, be usable because it involved copying many bits around in memory. Use BufferedImage to move offscreen images to system memory rather than copying pixels. For even faster image mapping, VolatileImage allows a hardware-accelerated offscreen image to be drawn directly on the video card. VolatileImage is support system study, volatile because the image can be lost at any time, from cafe, various causes: running another application in fullscreen mode; starting a screen saver; changing screen resolution; interrupting a task. Once. Only constantly re-rendered images need to cafe, be explicitly created as VolatileImage objects to be hardware accelerated. Such images include backbuffers (double buffering) and research on religion animated images. All other images, such as sprites, can be created with createImage, and Java 2D will attempt to accelerate them. Cafe Letter. If an image, such as a sprite, is research on religion, drawn once and copied from cover, many times, Java 2D makes a copy of it in accelerated memory and future copies from the image can perform better. To render sprites to the screen, you should use double-buffering by: creating a backbuffer with createVolatileImage, copying the sprite to the backbuffer, and copying the backbuffer to clinical decision case, the screen. If content loss occurs, Java 2D re-copies the sprite from software memory to accelerated memory.
Only some graphics operations (e.g. curved shapes) are accelerated on some platforms. Cafe. Use profiling to determine what works best for your situation. From 1.4 Swing uses VolatileImage for its double buffering. VolatileImage.getCapabilities() provides an ImageCapabilities object which gives details of the on religion, details of the runtime VolatileImage. The ImageCapabilities allows the application to decide to cover, use less images, images of on spring, lower resolution, different rendering algorithms, or various other means to letter, attempt to get better performance from the essay, current situation and platform.
Sun community chat session on Optimizing Java Program Performance with Peter Haggar. (Page last updated January 2001, Added 2001-02-21, Author Edward Ort, Publisher Sun). Tips: Try faster JVMs if possible. Cafe Cover Letter. Never tune code unless you have identified a performance problem with a profiling tool. Beware that tuning techniques may not work well on all platforms. Speed start-up time by: minimizing the .class sizes (use -g:none or a shrink tool e.g. Essay. DashO, JAX, JOpt); turn off the cafe letter, JIT Good design, data structures, and algorithms are the clinical system study, best things to produce good performance. Letter. Check String manipulation code. It is cause computer addiction, much more efficient to read data from disk all at once rather than with multiple reads. Cover Letter. Use the buffered classes when doing i/o. import is a compile time function, so has no effect on decision runtime (i.e. Cover. import a.b.*; or import a.b.c; make no difference to runtime performance). Optimize conditionals to have the most likely true results first. Java transaction management (JTS) (Page last updated April 2002, Added 2002-04-26, Author Brian Goetz, Publisher IBM).
Tips: A container managing transactions can identify communications to the same database, and automatically convert a two-phase transaction into a more efficient single-phase commit. Article about frameworks and the effective memory management of objects; avoiding memory leaks by design. (Page last updated January 2001, Added 2001-01-19, Author Leonard Slipp, Publisher Java Report). Tips: Define the effect computer, life cycles of objects and the duration of object interrelationships. Then manage objects according to whether the framework retains exclusive control of them, or whether the object can be accessed from outside the framework. Minimize the number of objects that can be accessed from outside the framework. In general, the creator of an object should be responsible for cafe cover, the objects' life cycle. Where this is not the case, the transfer of ownership of the eb white once to the lake, object should be explicit and emphasized. Cafe. Similarly object relationship management should be explicit and reversible: for every add() action, there must be a remove(); for every register() action, there must be a deregister(). Various strategies for connecting to databases (Page last updated March 2001, Added 2001-04-20, Author Prakash Malani, Publisher Java Report). Tips: Use pooled connections to what, reduce connection churn overheads. javax.sql.DataSource provides a standard connection pooling mechanism [example included]. Obtain and release pooled conections within each method that requires the cafe cover, resource if the connection is very short (termed Quick Catch-and-Release Strategy in the article).
However do not release the connection only to use it again almost immediately, instead hold the connection until it will not be immediately needed. The performance penalty of obtaining and essays survival releasing connections too frequently is quite small in cafe letter, comparison to potential scalability problems or issues raised because EntityBeans are holding on and fitness in younger to the connections for too long. The Quick Catch-and-Release Strategy is the cafe cover, best default strategy to ensure good performance and scalability. Basic article on performance tuning techniques. (Page last updated January 2001, Added 2000-12-14, Author Tarak Modi, Publisher Java Pro). Tips: [The compiler concatenates strings where they are fully resolvable, so don't move these concatenations to runtime with StringBuffer.] Where the compiler cannot resolve concatenated strings at compile time, the code should be converted to StringBuffer appends, and the StringBuffer should be appropriately sized rather than using the default size. Essay On Technology And Fitness Generation. Using the concatenation operator (+) in a loop is very inefficient, as it creates many intermediate temporary objects. Presizing collections (like Vector) to the expected size is more efficient than using the letter, default size and letting the collection grow. Removing elements from a Vector will necessitate copying within the Vector if the element is removed from anywhere other than the end of the collection.
Cache the decision case study, size of the collection in cafe cover letter, a local variable to use in paper on religion, a loop instead of repeatedly calling collection.size(). Cover Letter. Unsynchronized methods are faster than synchronized ones. [Article discusses applying these optimzations to a thread pool implementation.] Object creation tuning (Page last updated 2000, Added 2001-07-20, Author Daniel F. Savarese, Publisher Numega). Tips: Creating and dereferencing too many objects can adversely impact performance. Avoid holding on on religion and science to objects for too long by explicit dereference (setting variables to null) and by using weak references. Use a profiler to determine which objects may be created too often, or may not be being dereferenced. When looking for memory problems, look at methods that are called the most times or use the most memory.
Frequently called methods may unnecessarily allocate objects on each call. Methods that use a lot of memory may not need to use as much memory or they may be a source of memory leaks. Try to use mutable objects like StringBuffers or a char array instead of immutable objects like String. Letter. Don't restrict object state initialization to the arguments passed to a constructor. Eb White To The. Provide a zero-argument constructor that creates reasonable default values and include setter methods or an init method to allow objects of cover letter, that class to be reused. If you have to wrap primitive types, such as an int, define your own wrapper class which can be reused instead of using java.lang.Integer. Research Paper On Religion And Science. If you need to cafe cover letter, create many instances of on wilderness, a wrapper class like Integer, consider writing your algorithm to accept primitive types. Use a factory class instead of directly calling the new operator, to allow easier reuse of objects. Object pooling and database connection pooling are two techniques for reducing object creation overheads. Letter. Object pools can be sources or memory leaks and can themselves be inefficient. The java.nio packages (updated) (Page last updated December, 2001, Added 2001-10-22, Author John Zukowski, Publisher Sun).
Tips: Direct buffers have a higher creation cost than non-direct buffers because they use native system operations rather than JVM operations. Direct buffers optimize access operations by using the system's native I/O operations. Survival. Reduce threads by multiplexing I/O using selectors: The new I/O capabilities, allow you to create a Web server that does not require one thread per connection. How to Climb a B-tree (Page last updated December 2001, Added 2001-12-26, Author Rick Grehan, Publisher JavaPro). Tips: A B-tree outperforms a binary tree when used for external sorting (for example, when the index is cafe cover, stored out on on spring break essay disk) because searching a binary tree cuts the number of keys that need searching in half for every node searched, whereas B-tree searching cuts the number of keys that have to be searched by approximately 1/n, where n is the number of keys on a node. Cafe Cover. B-tree variants provide faster searching at the cost of slower insertions and deletions. Two such variants are the B-tree with rotation (more densely packed nodes) and the B+tree (optimized for sequential key traversing). [Article discusses building a B-tree class, and persisting it to provide a disk-based searchable index].
Database comparison (Page last updated February 2002, Added 2002-04-26, Author Timothy Dyck, Publisher E-Week). Tips: SQLServer has driver problems that slow access to it. Connection memory requirements vary dramatically between databases, and affect how much memory can be allocated to other resources. In-memory query result caches (such as with mySQL) improves performance significantly. (Works by decision system study, retrieving cached results of byte-for-byte identical queries, with no query compilation required). Add extra indexes. Arrange the stored order of rows to best satisfy the queries. Some drivers store the entire result set in cafe, memory when using bidirectional cursors - which does not scale. File Channels, StackTraceElements, (Page last updated May 2002, Added 2002-05-19, Author Glen McCluskey, Publisher Sun). Tips: File Channels (from the 1.4+ nio package) provide optimized mapping and a transferTo() method which is the fastest way to copy files. StackTraceElement provides access to research and science, the stack from excception objects, useful for analyzing stack elements.
Article about garbage collection and cafe cover finalization. (Page last updated December 2001, Added 2001-12-26, Author Jeff Friesen, Publisher JavaWorld). To The. Tips: [No specific performance tips, but its always helpful to know about GC]. Java Transaction Service (Page last updated March 2002, Added 2002-03-25, Author Brian Goetz, Publisher IBM). Cafe Cover Letter. Tips: Writing every data block to disk when any part of essay computer addiction, it changes would be bad for system performance. Deferring disk writes to a more opportune time can greatly improve application throughput.
Transactional systems achieve durability with acceptable performance by summarizing the cover letter, results of cause effect, multiple transactions in a single transaction log. Cover Letter. The transaction log is stored as a sequential disk file and will generally only be written to, not read from, except in the case of rollback or recovery. Writing an update record to i did on spring essay, a transaction log requires less total data to be written to disk (only the data that has changed needs to be written) and fewer disk seeks. Changes associated with multiple concurrent transactions can be combined into a single write to the transaction log, so multiple transactions per disk write can be processed, instead of requiring several disk writes per transaction. HTTP sessions vs. stateful EJB (Page last updated July 2002, Added 2002-07-24, Author Peter Zadrozny, Publisher Weblogic Developers Journal). Tips: The comparative costs of storing data in an HTTP session object are roughly the same as storing the same data in a stateful session bean. Failure to remove an EJB that should have been removed (from the HTTP session) carries a very high performance price: the EJB will be passivated which is a very expensive operation. Chapter 1, What Is Performance? of Java Platform Performance. Cafe Cover. (Page last updated 2000, Added 2001-11-27, Author Steve Wilson and Jeff Kesselman, Publisher Sun). Tips: Design your software with the target configuration (e.g. RAM) in mind. Essays. If your program consumes all of cover, your user's memory resources, they probably won't be happy.
Measure performance under loads comparable to expected deployed loads. Perceived performance is a highly important aspect of performance. How fast a program feels is cause effect essay addiction, more important than how fast it really is. Chapter 2, The Performance Process of Java Platform Performance. (Page last updated 2000, Added 2001-11-27, Author Steve Wilson and Jeff Kesselman, Publisher Sun). Tips: It's nearly impossible to achieve good performance through optimizations alone, without considering performance in analysis and design stages. Creating clear system and performance requirements is the key to evaluating the success of your project.
Use cases provide excellent specifications for building benchmarks. Specify the limitations of the cover letter, application: well-defined boundaries on the application scope can provide big optimization opportunities. Specifications should include system and performance requirements, including all supported hardware configurations (RAM/CPU/Disk/Network) and other software that normally executes concurrently. System. You should specify quantifiable performance requirements, for example a response time of two seconds or less. Scalability is more dependent on cafe letter good design decisions than optimal coding techniques. Encapsulation leads to survival, slowdowns from increased levels of indirection, but is essential in cover, large, scalable, high-performance systems. For example, using a java.util.List object may be slower than using a raw array, but allows you to essays survival, change very easily from ArrayList to LinkedList when that is faster. Meeting or exceeding your performance requirements should be part of the shipping criteria for your product.
Once you've determined that a performance problem exists, you need to begin profiling. Cafe Cover. Profilers are most useful for survival, identifying computational performance and cafe cover RAM footprint issues. Performance tuning is an iterative process. Data gathered during profiling needs to be fed back into decision support case study the development process. Chapter 3, Measurement Is Everything of Java Platform Performance. (Page last updated 2000, Added 2001-11-27, Author Steve Wilson and Jeff Kesselman, Publisher Sun). Cover. Tips: Benchmarks are typically time-related, but can also measure quantities such as how much memory is used. A stopwatch is a versatile benchmarking tool. Paper And Science. System.currentTimeMillis() provides millisecond timing for benchmarking [A Stopwatch class based on using System.currentTimeMillis() is presented]. Use benchmarks to: Compare the performance of alternative solutions; Profile performance; Track performance changes. Micro-benchmarks (repeatable sections of cafe letter, code) can be useful but may not represent real-world behavior.
Factors that can skew micro-benchmark performance include Java virtual machine warm-up time, and global code interactions. Macro-benchmarks (repeatable test sequences from the research paper and science, user point of view) test your system as actual end users will see it. Extract minima, maxima and averages from cover letter, repeated benchmark data for analysis. Use these to compare progress of benchmarks during tuning. [I like to add the 90th-centile value too]. Profilers help you find bottlenecks in applications, and should show: the methods called most often; the clinical system case study, methods using the largest percentage of time; the methods calling the most-used methods; and the methods allocating a lot of memory. The Sun JVM comes with the hprof profiler. Bottlenecks can be tuned by cafe cover, making often-used methods faster; and by calling slow methods less often.
Backtrace methods to understand the context of the bottleneck. For example, caching a value may be a better optimization than speeding up the repeated calculation of that value. Memory usage is often of critical importance to the overall application performance. Excessive memory allocation is often one of the first things that an clinical decision support case study experienced developer looks for when tuning a Java program. Examine bottlenecks for memory allocation. For example you may be able to cafe cover letter, replace a repeated object allocation in eb white once, a loop with a reusable object allocated once outside the loop.
Memory leaks (not releasing objects for the garbage collector to reclaim) can lead to a large memory footprint. You identify memory leaks by: determining that there is a leak; then identifying the objects that are not being garbage colleted; then tracing the references to those leaking objects to determine what is holding them in memory. If your program continues to use more and cover more memory then it has a memory leak. This determination should happen after all initializations have completed. Identify memory leak objects by marking/listing the objects in some known state, then cycling through other states and back to that known state and essays on wilderness survival seeing which extra objects are now present. When there are obvious bottlenecks, the cover letter, method profile should show these. A flat method profile is one where there are no obvious bottlenecks, no methods taking vastly more time than others. In this case you should look at cumulative method profiles, which show the cause, relative times taken by a method and all the methods it calls (the call tree ). This should identify methods which are worthwhile targets for optimization. Chapter 4, I/O Performance of Java Platform Performance: Strategies and cafe Tactics. (Page last updated 2000, Added 2001-12-27, Author Steve Wilson and Jeff Kesselman, Publisher Sun).
Tips: Buffer i/o operations. Custom buffering (using your own array of bytes/chars) is quicker than using a Buffered class. Application specific i/o can be tuned, e.g. caching in and fitness generation, memory frequently served pages of a HTTP server. Default Serialization is cafe cover, slow. Use the transient keyword to define fields to avoid having those fields serialized. Examine serialized objects to determine which fields do not need to be serialized for the application to work. Chapter 5, RAM Footprint of Java Platform Performance: Strategies and Tactics. (Page last updated 2000, Added 2001-12-27, Author Steve Wilson and Jeff Kesselman, Publisher Sun). Tips: Virtual memory is on spring essay, many times slower than RAM: try to cafe cover letter, fit the application into available RAM on the target platform.
Runtime.totalMemory() and research paper Runtime.freeMemory() measure available heap memory, but not the RAM footprint of the application. Use operating system monitoring tools to determine the RAM footprint of the application: e.g. task manager on Windows NT, pmap -x and ps on cafe letter Solaris. Small GUI apps need several hundred classes to be loaded just to start the app. Small GUI apps need to paper and science, reduce the cafe cover, number of classes loaded to improve startup time. You can approximate sizes of what, objects based on the number of fields and their types: byte-1 byte; char-2 bytes; short-2 bytes; int-4 bytes; float-4 bytes; long-8 bytes; double-8 bytes; references-4 bytes. JVMs will impose additional overheads. You can determine actual object sizes for a particular JVM by measuring the heap space taken by multiple instances of cafe, a class. Use profiling to determine the overal size cost of a class of objects, to essays, determine whether it is worth reducing the size cost of the class.
Some JVM/OS combinations can impose a significant memory overhead on each thread. Use 'java -verbose MyMainClass' to identify all classes that are loaded. Chapter 6, Controlling Class Loading of Java Platform Performance: Strategies and Tactics. (Page last updated 2000, Added 2001-12-27, Author Steve Wilson and Jeff Kesselman, Publisher Sun). Tips: To avoid loading unnecessary classes (e.g. when the JIT compiles methods which refer to unused classes), use Class.forName() instead of directly naming the class in cafe cover letter, source. This tactic is useful if large classes or a large number of classes are being loaded when you don't think they need to research and science, be. Combine listener functionality into one class to avoid an explosion of cafe cover, generated inner classes. Essay In Younger Generation. This technique increases maintenance costs.
Use a Generic ActionListener which maps instances to method calls to avoid any extra listener classes. This has the drawback of losing compile-time checks. java.lang.reflect.Proxy objects can be used to generalize this technique to multiple interfaces. Run multiple applications in the same JVM. Cafe Cover Letter. [Chapter discusses how to do this, but see Multiprocess JVMs and Echidna for more comprehensive solutions]. Chapter 7, Object Mutability: Strings and eb white essay lake other things of Java Platform Performance: Strategies and Tactics. (Page last updated 2000, Added 2002-02-22, Author Steve Wilson and Jeff Kesselman, Publisher Sun). Tips: The allocation, initialization, and collection of many short-lived useless objects can cause major inefficiencies in your software, even when running on an advanced runtime such as the HotSpot VM. Cafe Letter. Be cautious when the number of decision support case, objects you're allocating becomes very high-for example, when allocating objects inside loops.
For heavy-duty text processing, however, some uses of the cover, String class can become major performance bottlenecks. StringBuffer can be used to improve the performance of common text processing operations. Avoid creating new strings in compute intensive parts of code. Essay Addiction. Be careful of the cover letter, concatenation operators '+' and '+=' when used with strings. Essay Once More To The Lake. To avoid spurious object creation, create methods which return primitive data for multiple data items, rather than one method returning an object holding multiple data items.
Use immutable objects to prevent the need to copy objects to pass information between methods. Object pooling small objects is often counterproductive. The overhead of managing the object pool is cafe cover letter, often greater than the small object penalty. Pooling can also increase a program's memory footprint. And Fitness. Pooling large objects (e.g. large bitmaps or arrays) or objects that work with native resources (e.g. Threads or Graphics) can be efficient.
Chapter 8, Algorithms and data structures of letter, Java Platform Performance: Strategies and Tactics. (Page last updated 2000, Added 2002-02-22, Author Steve Wilson and Jeff Kesselman, Publisher Sun). Tips: Choosing the best algorithm or data structure for a particular task is one of the keys to writing high-performance software. On Wilderness. The optimal algorithm for cafe letter, a task is highly dependent on the data and data size. Special-purpose algorithms usually run faster than general-purpose algorithms. Essays. Testing for easy-to-solve subcases, and using a faster algorithm for those cases, is a mainstay of cover letter, high-performance programming. Research On Religion. Collection features such as ordering and duplicate elimination have a performance cost, so you should select the cover letter, collection type with the fewest features that still meets your needs.
Most of the time ArrayList is the best List choice, but for some tasks LinkedList is more efficient. HashSet is much faster than TreeSet. Essays Survival. Choosing a capacity for HashSet that's too high can waste space as well as time. Set the initial capacity to about twice the size that you expect the Set to grow to. The default hash load factor (.75) offers a good trade-off between time and space costs. Higher values decrease the space overhead, but increase the time it takes to look up an entry. Letter. (When the number of entries exceeds the product of the load factor and the current capacity, the capacity is doubled). Programs pay the essay more lake, costs associated with thread synchronization even when they're used in cafe, a single-threaded environment. The Collections.sort() method uses a merge sort that provides good performance across a wide variety of situations. When dealing with collections of primitives, the overhead of allocating a wrapper for each primitive and then extracting the primitive value from the wrapper each time it's used is quite high.
In performance-critical situations, a better solution is to work with plain array structures when you're dealing with collections of primitive types. Random number generation can take time. If possible you can pre-generate the random number sequence into an array, and use the elements when required. Chapter 10 (Swing models and renderers) of Java Platform Performance: Strategies and Tactics. (Page last updated 2000, Added 2000-10-23, Authors Steve Wilson, Jeff Kesselman, Publisher Sun). Tips: Swing?s model-view architecture is critical for building scalable programs. Cause Effect Essay Addiction. When changing data stored in models, perform the operations in bulk whenever possible. E.g. use the interface that adds an array of elements rather than one element at a time. Letter. Use custom models to handle large datasets.
The default models provided with Swing are generic and study designed for letter, light-duty use [i.e. Essay. are slow]. Custom renderers can sometimes be used to cafe cover, improve performance. But watch out as it is easy to badly construct a custom renderer, making performance worse. A custom model and a custom renderer can be used together in the same Component. When initializing or totally replacing the contents of a model, consider constructing a new one instead of research on religion and science, reusing the existing one, as this avoid posting notifications to any listeners. Cover Letter. [Or reuse the object but deregister the listeners first]. Improving socket transfer rates (Page last updated May 2001, Added 2001-05-21, Author Rama Roberts, Publisher Sun). Essay Once Lake. Tips: The usual StringBuffer better than String tip applies to socket communications too. PrintWriters are not suitable for socket communications because they flush at each newline. Socket.setTcpNoDelay(true) may help speed if you have many small packets sent frequently across the connection. Server performance testing (Page last updated 2000, Added 2001-05-21, Author Floyd Marinescu, Publisher The Server Side). Tips: Test response times against average current data/user volumes, then repeat the same test against four times as much volume as you expect in 3 years time.
This defines your long term target - getting the cafe, response times the on spring break essay, same for that latter test. Response time increasing too much when database is over populated probably indicates lack of or inappropriate indexing on the database. Response time increasing exponentially as load increases, you need to improve scalability by cafe, optimizing the application or adding resources. Use SQL clause with EXPLAIN or similar (e.g. Explain select * from table where tablefield = somevalue) to ensure that the and fitness generation, database is doing an cover letter indexed search rather than a linear searches of large datasets. Use a profiler to determine object usage, garbage collection behaviour and decision system study method bottlenecks in the application. Minimize network calls, especially database calls: make one large database call rather than many small ones; make sure ejbStore isn?t storing anything for read only operations; use Details Objects to get entity bean state rather than making many trips for each aspect of state. Use caching where possible. Use session beans as a fa?ade to your entity beans to encapsulate the workflow of one entire usecase in one network call to one method on a session bean (and one transaction). Optimizing entity beans (Page last updated May 2001, Added 2001-05-21, Author Akara Sucharitakul, Publisher Sun). Tips: Use container-managed persistence when you can.
An efficient container can avoid database writes when no state has changed, and cover letter reduce reads by essays survival, retrieving records at cafe cover the same time as find() is what on spring essay, called. Minimize database access in ejbStores. Use a dirty flag to avoid writing tee bean unless it has been changed. Always cache references obtained from cafe cover, lookups and find calls. Always define these references as instance variables and look them up in the setEntityContext (method setSessionContext for session beans). Always prepare your SQL statements. Close all database access/update statements properly. Avoid deadlocks.
Note that the sequence of ejbStore calls is not defined, so the developer has no control over the access/locking sequence to database records. EJB best practices (Page last updated April 2001, Added 2001-05-21, Author Sandra L. Emerson, Michael Girdley, Rob Woollen, Publisher Java Developers Journal). Tips: To avoid resources being held unnecessarily for clinical support case, long periods, a transaction should never encompass user input or user think time. Cafe Letter. Container managed transactions are preferred for consistency, and should provide extra optimization options. Break Essay. Don't model a shared cache or any shared resource as a stateful session bean. Letter. Stateless session beans are easier to scale than stateful session beans. With stateful session beans, every client will need its own session bean instance, reducing scalability. Always call remove after finishing with a stateful session bean instance, otherwise the EJB container will eventually passivate the bean, incurring extra unnecessary disk writes. J2EE clustering (Page last updated August 2001, Added 2001-08-20, Author Abraham Kang, Publisher JavaWorld). Cause Computer Addiction. Tips: Consider cluster-related and load balancing programming issues from the beginning of the development process. Letter. Load balancing has two non-application options: DNS (Domain Name Service) round robin or hardware load balancers. [Article discusses the pros and cons].
To support distributed sessions, make sure: all session referenced objects are serializable; store session state changes in eb white essay once lake, a central repository. Try to keep multiple copies of objects to a minimum. SoftReference-based HashMap (Page last updated August 2001, Added 2001-08-20, Author Heinz Kabutz, Publisher Kabutz). Cover Letter. Tips: WeakHashMaps are not ideal if you want the cause effect, values to be weakly referenced rather than the keys. SoftReferences may be better for memory sensitive caches since they are supposed to be collected in cover letter, the reverse order to which they were last referenced. Adding the capability to essay and fitness generation, strongly reference some of the values ensures those objects will be retained through a garbage collection. Avoiding memory leaks in EJBs (Page last updated April 2001, Added 2001-05-21, Author Govind Seshadri, Publisher IT World). Tips: Make sure that any beans which have session scope implement the HttpSessionBindingListener interface Explicitly release any resources that may be used within the cafe cover, bean by implementing the valueUnbound() callback. Explicitly release the user's session by invoking invalidate() when they log out.
Try setting the session invalidation interval to effect computer, a smaller value than the default 30 minutes. Make sure that you are not placing any large grained objects into cover letter the servlet context (application scope) as that can also prove problematic sometimes. Parallel clustering of machines using Java (Page last updated April 2001, Added 2001-04-20, Author Aashish N. Patil, Publisher IBM). Tips: [Article describes an clinical system case implemented architecture for distributing Runnable threads across multiple computer nodes]. The Javap disassembler (Page last updated August 2000, Added 2001-04-20, Author Stuart Halloway, Publisher Sun). Cafe. Tips: [Article describes using the eb white once more, javap disassembler, useful for identifying exactly what the code has been compiled into]. Cover. Use the javap disassembler to determine the efficiency of generated bytecodes. Clinical Decision Support System Study. javap is not sufficient to determine code efficiency, because JIT compilers can apply additional optimizations. Speeding up file searching in cafe cover, JFileChooser (Page last updated February 2001, Added 2001-03-21, Author Slav Boleslawski, Publisher JavaWorld).
Tips: [Article discusses JFileChooser's operation in detail, including multi-threading, filename caching and batched delivery. Article discusses how to essay, add type-ahead lookup functionality to choosing files]. Various tips. (Page last updated 1999?, Added 2000-10-23, Author Nate Sammons, Publisher Sammons). Tips: Use StringBuffer for String concatenations, rather than the '+' operator. Use static strings, String.intern() or a static Hashtable to cafe letter, reduce the number of occurrances of identical string objects. Modify java.lang.String to cache the hashCode if you are using many string keys in hash tables [note Sun added this optimization to the String class in SDK 1.3] String.getBytes() is i did, very inefficient with a method call for cafe, every character.
Use getBytes(int, int, byte int) instead, or some other mecahnism. Use non-synchronized Vector, Hashtable, etc. where possible. Size Vector, Hashtable, etc. appropriately. Object creation is expensive. Research On Religion And Science. Pool your objects where possible. Inner class object creation is even more expensive than normal. Cafe. Use non-public concrete support classes instead. Method call times: static 220ns; final 300ns; instance 550ns; interface methods 750ns; synchronized methods 1,500ns. Paper And Science. [But times vary enormously depending on the VM and context]. Use static final methods where possible. [And do functional programming too ;-)] Rewrite loops so that the termination test compares against 0. Use exception terminated infinite loops for long loops. Use System.arraycopy() to copy arrays. Use temporary local variables to manipulate instance variables.
EJB2 clustering with application servers (Page last updated December 2000, Added 2001-01-19, Author Tyler Jewell, Publisher OnJava). Tips: [Article discusses multiple independent ways to load balance EJBs] Sun community chat session with Steve Wilson and Jeff Kesselman on Java Performance (Page last updated August 2000, Added 2001-01-19, Author Edward Ort, Publisher Sun). Tips: HotSpot JVMs can return heap memory to the OS while running. HotSpot Client VM (JVM 1.3) is optimized for quick startup time and low-memory footprint. Cover. The server VM (HotSpot 1.0/2.0) is designed for peak performance (may take a little longer to get up-to-speed but it will go faster in the end). Always use System.arraycopy to research on religion, copy arrays.
Sticky applets available with the 1.3 plugin speeds startup (persistently caches classes on clients). Also put resources together into jar file to reduce download requests. SwingSet2 (demo in cafe letter, SDK distribution) provides a good example of large numbers of Swing components in a window, created asynchronously. Don't use use finalizers for anything that must be done in a timely manner. Use primitives and i did on spring transients to cafe, speed up serialization. Use a concentrator object to limit the research on religion, repaint events to once every 100 milliseconds in heavily loaded systems and in multi-threaded swing environments. There is some overhead for cafe, context switching (using invokeLater) into the AWT-event thread, which you want to minimize. Clinical Case Study. The key to high performance code is organization and process.
Write clean, well encapsulated code, then use a Profiler to find your true bottlenecks and letter tune those. Experiences building a servlet (Page last updated June 2001, Added 2001-06-18, Author Asif Habibullah, Jimmy Xu, Publisher Java Pro). Tips: Keep the size of the client tier small so that downloads are fast. Use the servlet init() and destroy() methods to start and stop limited and expensive resources, such as database connections. Make the servlets thread-safe and use connection pooling. Essay On Technology And Fitness Generation. Use PreparedStatements rather than plain Statement objects. Use database stored procedures.
Typesafe Enumeration gotchas (Page last updated January 2002, Added 2002-01-25, Author Vladimir Roubtsov, Publisher JavaWorld). Tips: Implement readResolve() for Serializable Enumeration classes to maintain object identity. Ensure that the same Classloader always loads the Enumeration class to cafe cover, maintain object identity. Reference objects (Page last updated January 2002, Added 2002-01-25, Author Jeff Friesen, Publisher JavaWorld). Tips: Cache objects such as images in memory for essays, quicker presentation after the first display request. Use Reference objects to hold cached objects so that the garbage collector can free space when required. [Article discusses in detail the various Reference object types]. Optimizing Java for intensive numeric calculations (Page last updated January 2002, Added 2002-02-22, Author James W. Letter. Cooper, Publisher DevX). Tips: Allocating on the heap (as with object creation) is paper on religion, much slower than allocating on cover the stack.
Making numbers into first-class objects imposes a significant overhead on calculations. Hand applied optimizations may be superceded by future compiler optimizations. Use specialized subtypes to support system study, reduce dynamic dispatching. Replace objects with their data held and passed as local variables. OS Signal handling in Java (Page last updated January 2002, Added 2002-02-22, Author Chris White, Publisher IBM). Tips: [Article describes how to handle operating system signals from within Java. Useful if you want your application to be able to respond to the full gamut of system and user actions].
Natively compiled code from Java source (Page last updated January 2002, Added 2002-02-22, Author Martyn Honeyford, Publisher IBM). Tips: Natively compiled code generated from Java source might be faster and might require less memory and disk resources. [But this articles show some JVMs can be faster]. When you include the cafe cover letter, disk size of the JVM libraries, a natively compiled Java application is significantly smaller in essay on technology in younger, disk size. When considering compiling Java applications to native code determine exactly what problem (or problems) you are hoping to solve with native compilation, and try all the available native compilers. RMI arguments (Page last updated December 2001, Added 2002-02-22, Author Scott Oaks, Publisher Java Report). Tips: Some application servers can automatically pass parameters by reference if the communicating EJBs are in the same JVM.
To ensure that this does not break the application, write EJB methods so that they don't modify the parameters passed to them. Choosing an application server (Page last updated January 2002, Added 2002-02-22, Author Sue Spielman, Publisher JavaPro). Tips: A large-scale server with lots of traffic should make performance its top priority. Performance factors to consider include: connection pooling; types of cafe cover letter, JDBC drivers; caching features, and their configurability; CMP support. Inability to scale with reliable performance means lost customers. Scaling features to consider include failover support, clustering capabilities, and load balancing. Notated keys to access elements of nested Maps. (Page last updated January 2002, Added 2002-02-22, Author Matt Liotta, Publisher DevX). Tips: Use dot separated, concatenated strings to optimize access to elements of nested Maps by caching elements in what, the top level Map. The Garbage Collector (Page last updated January 2002, Added 2002-01-25, Author Phil Vickers, Publisher IBM).
Tips: In most current JVMs (prior to 1.4) GC starts off by locking out all other threads in the JVM. GC is a stop-the-world, synchronous operation. Non-generationl GC requires scanning the stacks of every thread and the entire Java heap. Calling System.gc() explicitly is not good for cover letter, performance, as it can be called when GC is not necessary, but will still result in a long pause of all JVM operations. Object management (Page last updated January 2002, Added 2002-01-25, Author Mark Bluemel, Publisher IBM). Tips: Avoid retaining objects accidentally, by holding references beyond an eb white essay once more to the lake appropriate time for their release.
Use profiling tools to identify unintentionally retained objects. Garbage collection is not free; other processing will be paused during GC. Try to reuse objects in preference to discarding and re-creating them. JViewport scrolling performance (Page last updated January 2002, Added 2002-01-25, Author Heather Brailsford, Publisher IBM). Tips: JViewport.BLIT_SCROLL_MODE is the cafe cover letter, default scrolling mode for JViewport in SDK 1.3 (available since 1.2.2). This mode paints directly to the screen instead of being buffered offscreen. This normally provides optimal performance and minimum memory requirements. However complex images may display some intermediate paint operations if the painting is not fast enough, giving jerky or flashing images. If this is survival, unacceptable, try the cover letter, alternate modes: setScrollMode(BACKINGSTORE_SCROLL_MODE) (intermediate performance, higher memory requirements); or setScrollMode(JViewport.SIMPLE_SCROLL_MODE) (slowest). Using JNI Get* calls (Page last updated January 2002, Added 2002-01-25, Author Mark Bluemel, Publisher IBM).
Tips: If you use JNI Get* calls (for example, GetStringCritical), you must always use the what i did break, corresponding Release* call (for example, ReleaseStringCritical) when you have finished with the data, even if the isCopy parameter indicates that no copy was taken. Servlet 2.3 events (Page last updated January 2002, Added 2002-01-25, Author Budi Kurniawan, Publisher DevX). Tips: The Servlet 2.3 specification adds application and session events. [Event driven applications can often be scaled more easily than process driven applications]. Sun presentation on J2SE performance strategies (originally accessed from Reginald Hutcherson's page) (Page last updated May 2001, Added 2001-06-18, Author Reginald Hutcherson, Publisher Sun). Tips: The Sun 1.3 JVM has a significantly faster startup time compared to any earlier Sun release. Improve bytecode (method) execution by: using JITs; reducing (byte-)code size; profiling code to eliminate bottlenecks. Reduce garbage collection overheads by: reducing the number of objects generated; reusing objects; caching objects. Cover Letter. Reduce multithreading overheads by targeting the granularity of locks, and managing synchronization correctly.
Other operations which improve performance include: using JAR files; using arrays rather than collections; using primitive types rather than objects. If the essays survival, CPU is the bottleneck, target: code; method profiler identified bottlenecks; algorithms; and object creation. If system memory is the bottleneck, try to avoid paging by targeting: large objects; arrays; the application design. If disk I/O is the bottleneck, identify the problem and eliminate it. Ensure that you have benchmarks and targets, and letter run reproducible benchmark tests. Target the easiest of the top 5 methods, or the cause, top method, identified by method profiling. Repeat profile, fix, benchmark iterative process. Letter. Avoid runtime String concatenation. Use StringBuffer instead.
Local variables (method arguments and tempoararies) remain on the stack and are much faster than heap variables (static, instance new objects). Research Paper On Religion. Use strength reduction: x = x + 5 - x += 5; y = x/2 - y = x 1; z = x * 4 - z = x Always profile the letter, code to find where the bottlenecks are. And Fitness In Younger Generation. equalsIgnoreCase() is faster than equals() in most cases (except where string sizes are the same). Cafe Letter. Loop backwards rather than forwards [actually its the comparison to 0 that matters]. Reduce code size by: obfuscating code; compression in jar files; excluding the manifest in jar files; reordering variable declarations; eliminating dead code; using protected methods. Manipulate data that requires parsing into a format that is essays on wilderness survival, easier to parse. Use bitshift instead of cafe cover letter, multiplying or dividing by powers of 2. Use binary-And (on N-1) instead of modulus (on N). Use Thread.sleep() instead of paper and science, a for loop for measured delays.
Use the update() method to draw things, not the paint() method. Use double-buffering. Apply faster algorithms and data structures. Use StringBuffer for String concatenations, rather than the '+' operator. Use static [pre-created] exceptions. Use final classes. Javabean component architecture (Page last updated October 2001, Added 2001-10-22, Authors David Hardin and Mike Frerking, Publisher Java Developers Journal). Tips: Reusing events reduce object creation and garbage collection overheads. Letter. Passing primitive data types directly to event handlers is the fastest way to pass event information. Generic events reduce the number of (inner) classes required to essays on wilderness survival, handle the events. The logging APIs (Page last updated September 2001, Added 2001-10-22, Author Tom Harpin, Publisher Sun).
Tips: [Article gives a high level view of the logging APIs introduced in SDK 1.4. No application is adequately deployed unless it has some performance logging in place]. The performance of cafe letter, games on J2ME (Page last updated March 2001, Added 2001-03-21, Author Jason R. Briggs, Publisher JavaWorld). Tips: Target performance for processors that you will run on when the research paper, project is deployed. Implementing the ImageProducer interface and setting an image's pixels directly eliminates one or two steps in the MemoryImageSource option and seems to be about cover letter 10 percent to 20 percent faster on computer average. Raw frame rate display, without taking account of the time taken to draw an image, runs from cover letter, 2 frames per second (fps) to 400 fps, depending on processor and JVM. The PersonalJava runtime has no JIT, and provides the worst performance. With a JIT it might be usable. [Article includes references to a number of hardware based Java implementations, i.e.
Java enabled CPUs.] Introductory level article on threading applets (Page last updated March 2001, Added 2001-03-21, Author Monica Pawlan, Publisher Sun). Tips: Multi-threaded programs can allow multiple activities to continue without blocking the user. Spawning additional threads carries extra memory and processor overhead, but can easily be worth the overheads. Applets need a separate timer thread to execute any non-short tasks so that the applet remains responsive to the browser.
The volatile modifier requests the Java VM to always access the shared copy of the variable so the its most current value is always read. If two or more threads access a member variable, AND one or more threads might change that variable's value, AND ALL of the threads do not use synchronization (methods or blocks) to read and/or write the value, then that member variable must be declared volatile to ensure all threads see the changed value. Cute tip on unblocking a blocked socket by sending it data from a timer thread. (Page last updated 1997, Added 2000-10-23, Author Albert Lopez, Publisher JavaWorld). Tips: Use a separate timer thread to timeout socket operations Instead of killing the blocked socket, send it some data to unblock it. J2EE design optimizations (Page last updated September 2001, Added 2001-10-22, Author Vijay S. Ramachandran, Publisher Java Developers Journal). And Fitness. Tips: For data that changes infrequently (i.e. rarely enough that a user session will not need that data updating during the session lifetime), avoid transactional access by using a cached Data Access Object rather than the transactional EJB (this is called the Fast Lane Reader pattern). Don't transfer long lists of cafe cover letter, data to the user, transfer a page at a time (this is called the Page-by-Page Iterator pattern). Instead of making lots of on spring break essay, remote requests for data attributes of an object, combine the cafe cover letter, attributes into another object and send the object to the client. Essay Once More To The. Then the attributes can be queried efficiently locally (this is cafe cover letter, called the Value Object pattern). Consider caching the value objects where appropriate. Choosing a J2EE application server, emphasizing the importance of essays on wilderness, performance issues (Page last updated February 2001, Added 2001-02-21, Author Steve Franklin, Publisher DevX).
Tips: Application server performance is letter, affected by: the JDK version; connection pooling availability; JDBC version and optimized driver support; caching support; transactional efficiency; EJB component pooling mechanisms; efficiency of webserver-appserver connection; efficiency of i did essay, persistence mechanisms. Your application server needs to be load tested with scaling, to determine suitability. Always validate the performance of the app server on cafe cover the target hardware with peak expected user numbers. Decide on clinical support system case study what is cafe letter, acceptable downtime for your application, and research paper on religion and science ensure the cover letter, app server can deliver the required robustness. High availability may require: transparent fail-over; clustering; load balancing; efficient connection pooling; caching; duplicated servers; scalable CPU support. Servlet Filters (Page last updated June 2001, Added 2001-07-20, Author Jason Hunter, Publisher JavaWorld). Clinical Decision Support Case Study. Tips: Servlet Filters provide a standardized technique for wrapping servlet calls. You can use a Servlet Filter to cover letter, log servlet execution times [example provided].
You can use a Servlet Filter to compress the webserver output stream [example provided]. Implementing clustering on a J2EE web server (JBoss+Jetty) (Page last updated September 2001, Added 2001-10-22, Author Bill Burke, Publisher OnJava). On Wilderness. Tips: Clustering includes synchronization, load-balancing, fail-over, and distributed transactions. [article discusses implementing clustering in cafe cover, an environment where clustering was not previously present]. I Did Break. The different EJB commit options affect database traffic and cover performance. Research And Science. Option 'A' (read-only local caching) has the smallest overhead. Hardware load balancers are a simple and fast solution to cafe cover, distributing HTTP requests to clustered servers. Making HTTP connections using background threads. (Page last updated September 2001, Added 2001-10-22, Author Eric Giguere, Publisher Sun). Tips: The user interface must always be responsive to the user's interaction. The application should respond to input no later than a tenth of research paper on religion, a second after it occurs: longer delays are noticed by cafe cover, the user, and make the on wilderness, user interface seem unresponsive.
So don't do more than about cafe cover a tenth of on spring, a second's worth of work in the user-service thread in cover letter, response to any user interface event. Use separate threads to perform operations that will last longer than one tenth of once more, a second. Provide the user with the option to cancel the operation at any time. [Article provides an cafe cover example of making an HTTP connection following these suggestions]. Article by survival, Frederic Boulanger with tuning tips. (Page last updated June 1998, Added 2000-10-23, Author Frederic Boulanger, Publisher Macadamian). Tips: Choose the best algorithm or data structure. Letter. Whatever can be calculated outside of a loop should be calculated outside of the loop.
Try to minimize method calls within a loop. Reduce the essay once to the lake, number of references to an array in loops. Store the value of array or array elements in temporary variables and cover use these in the loop. For multidimensional arrays store a reference for the currently accessed row in a variable. Store member variables in decision system study, a local temporary variable in cafe cover, loops. IBM's list of Java performance tuning tips (same page, two URLs). (Page last updated 2000, Added 2000-10-23, Author ?, Publisher IBM). Tips: Group native operations to reduce the number of JNI calls. Primitive types are faster than classes encapsulating types. Avoid excessive writing to the java console. Reorder CLASSPATH so that the most used libraries occur first. Clinical System Case Study. Don't overuse synchronized methods.
Use int instead of cafe cover letter, long when possible. Paper On Religion. When possible, declare methods as final. If needed, only call the garbage collector explicitly at an appropriate time (when things are quiet). Prudent use of zip and jar formats can improve load time. Cafe Letter. Compile java files with the optimizer on. Cache frequently used objects when possible. Use static final when creating constants. Use StringBuffer when doing excessive string manipulations. Consider when to use local variables in loops (speed vs. memory?).
Vectors are more flexible than arrays, but much slower. It is faster to add/delete items from the end of the vector. Avoid unnecessary casts and instanceof. On Technology Generation. Scope of variables can impact performance. EJB2.0 Container-Managed Persistence (Page last updated July 2001, Added 2001-08-20, Author Beth Stearns, Publisher Sun).
Tips: EJB 2.0 Container-Managed Persistence provides local interfaces which can avoid the cafe letter, performance overheads of remote interfaces. FAQ site with a couple of support study, basic performance tips. (Page last updated 2000, Added 2000-10-23, Author Martin Webb, Publisher IRT). Tips: FAQ 4002: Use an cafe cover letter ImageObserver (method listed in FAQ) to paper on religion, control how and cafe cover letter when images are painted during loading. FAQ 4003: Minimise flicker in animations by overriding update() to simply call paint() (default action is to clear the on wilderness survival, image first), and cover letter use double buffering. FAQ 4063 4066: Use jar files to reduce the amount of time that it takes to essay on technology and fitness in younger generation, download an applet. Anonymous inner classes (Page last updated December 2000, Added 2002-04-26, Author Heinz M. Kabutz, Publisher Kabutz).
Tips: Accessing private data members of an outer class, is done using a generated method, which is cafe, slower than normal field access. Though HotSpot can inline the effect computer, access. Minimizing space taken by HTTP downloads (Page last updated October 2001, Added 2001-10-22, Authors Gary Adams and Eric Giguere, Publisher Sun). Tips: Use HttpConnection.getLength() to determine the number of bytes needed to to hold the data from a download. Cafe Letter. Use a ByteArrayOutputStream to accumulate results if the content length is indeterminate. Cause Computer. The best performance is obtained from a 1.1 compliant webserver using persistent connections. Double-if on multi-CPU (Page last updated February 2002, Added 2002-03-25, Author Phil Vickers, Publisher IBM). Tips: Double-if logic fails on multiple CPU machines. You need to cafe letter, synchronize around double-if logic for more to the, consistent results, though this may be inefficient.
Faster JSP with caching (Page last updated May 2001, Added 2001-05-21, Author Serge Knystautas, Publisher JavaWorld). Tips: The (open source) OSCache tag library provides fast in-memory caching. Cache pages or page sections for letter, a set length of time, rather than update the page (section) with each request. Essays Survival. Caching can give a trade-off between memory usage and CPU usage, especially if done per-session. This trade-off must be balanced correctly for optimal performance. Scaling web services (Page last updated June 2001, Added 2001-07-20, Author Simeon Simeonov, Publisher XML Developers Journal). Tips: Use bigger, better, faster hardware, but there is a limit to the scalability of a single server: most application performance does not scale linearly with increases in the hardware power. Use more than one server in letter, a cluster that services requests as if it were a single server using: OS-level clustering (OS level built in clinical case study, failover mechanisms); Software load balancing (using a loda-balancing front-end dispatcher); Hardware load balancing (e.g.
DNS round-robin to cover letter, different servers). A basic load-balancing scheme is decision support case study, achievable by sending documents with different binding addresses (differnent URL hosts) Use faster communication protocols (e.g. plain sockets) Support asynchronous request processing message based interactions. Multithreaded Swing Applications (Page last updated September 2001, Added 2001-10-22, Author Monica Pawlan, Publisher Sun). Tips: Use the SwingUtilities.invokeAndWait() and SwingUtilities.invokeLater() methods to put code on the GUI eventr queue. Spawn threads for long operations so that the user does not get a blocked GUI.
Timers and low-level GUI display effects (Page last updated September 2001, Added 2001-10-22, Author Roman Bialach, Publisher Micro Java). Tips: You need a scheduling mechanism to perform animation, scrolling, updating the letter, display, etc. The paint() method on the Canvas is called by research on religion, the system only if it thinks that it needs to cafe cover, repaint it. So we need another timer to repaint the screen on a regular basis. Use a timer to periodically call repaint(). Architecting and Designing Scalable, Multitier Systems (Page last updated August 2001, Added 2001-10-22, Author Michael Minh Nguyen, Publisher Java Report).
Tips: Separate the UI controller logic from the servlet business logic, and let the controllers be mobile so they can execute on the client if possible. Clinical Decision Study. Validate data as close to cafe cover, the data entry point as possible, preferably on the client. Essays Survival. This reduces the network and server load. Business workflow rules should be on the server (or further back than the front-end). You can use invisible applets in a browser to validate data on the client. Sun community discussion on cafe cover Optimizing Entity Beans with Akara Sucharitakul (Page last updated June 2001, Added 2001-07-20, Author Edward Ort, Publisher Sun).
Tips: Prepared SQL statements get compiled in study, the database only cafe cover letter, once, future invocations do not recompile them. The result of research paper on religion and science, this is a decrease in the database load, and an increase in performance of up to 5x. Container Managed Persistence (CMP) can provide 2-3x better performance than Bean Managed Persistence (BMP). Optimizing dynamic web pages (Page last updated July 2001, Added 2001-07-20, Author Helen Thomas, Publisher Java Developers Journal). Cafe Letter. Tips: Dynamic generation of web pages is more resource intensive than delivering static web pages, and can cause serious performance problems. Essay Computer. Dynamic web page generation incurs overheads from: accessing persistent and/or remote resources/storage; data formatting; resource contention; JVM garbage collection; and script execution overheads. Dynamic content caching tries to mitigate Dynamic web page generation overheads by reusing content that has already been generated to cafe cover letter, service a request. JSP cache tagging solutions allow page and fragment level JSP output to be automatically cached.
On highly personalized sites page-level caching results in research on religion and science, low cache hit rates since each page instance is unique to a user. Component-level caching applies more extensively when components are reused in many pages, but requires manual identification of letter, bottleneck components. J2ME apps, with a discussion of the needs to balance performance (Page last updated June 2001, Added 2001-07-20, Author Glenn Coates, Publisher Java Developers Journal). Clinical Decision Support System Case. Tips: J2ME devices have limited processing power, so performance is important and must be considered for the target device. JIT compiled or natively compiled code is preferred, but may be unobtainable because of memory resource or deployment considerations.
JVM Interpreters have a significantly lower memory overhead compared to cover, JIT/HotSpot JVMs, but are much slower. Selectively compiled code might provide a good compromise of speed and memory if deployment considerations allow. The application does not need to be lightning fast in order to have a responsive user interface. The perception of lake, speed is important, for example, the user interface should give immediate feedback. JVM slection for the J2ME device is pivotal to cover letter, achieving the required performance. Compared to desktop environments, embedded systems typically have: lower memory availability; less processing power; user Interface restrictions; reduced communication bandwidth or unreliable connections; battery power; higher reliability requirements; lack of a file system. Tuning JVMs for servers. On Wilderness Survival. (Page last updated February 2002, Added 2002-03-25, Author Timothy Dyck, Publisher E-Week).
Tips: Multiple JVMs are often available for a particular platform. Choose the JVM that best suits your needs. Cover. The test here found setting min and max heaps to the same value provided the best performance. Limiting each Sun 1.3 JVM to using two CPUs (test used multiple JVMs and 6 CPUs) provided a 30% reduction in CPU usage. IBM JVMs did not require (or benefit from) this optimization. Data compression (Page last updated December 2001, Added 2001-12-26, Author Tony Sintes, Publisher JavaWorld).
Tips: [Article covers how to research on religion and science, add zip compression to letter, RMI communications]. Creating Web-based, interactive graphics. Eb White Essay Once To The Lake. (Page last updated December 2001, Added 2001-12-26, Author Steve Lloyd, Publisher DevX). Tips: If an applet parameter's [tags in the webpage] length is too long, the Web page's responsiveness begins to bog down. Move all but the essential parameters from the APPLET tag to letter, a dedicated HTTP link between the applet and what on spring the servlet. Cover. This allows page loading and break essay applet initialization to cover, occur at the same time over what on spring break, separate connections. Close java.sql.Statements when finished with. Inverting booleans (Page last updated February 2002, Added 2002-03-25, Author Heinz M. Cover Letter. Kabutz, Publisher Kabutz). Tips: The fastest way to invert a boolean is to essays on wilderness, XOR it (bool ^= true). Be careful when making performance measurements with HotSpot because the optimizing compiler can kick in to adjust results. The Proxy design pattern. (Page last updated February 2002, Added 2002-03-25, Author David Geary, Publisher JavaWorld).
Tips: Creating images is expensive. ImageIcon instances create their images when they are constructed. If an application creates many large images at once, it could cause a significant performance hit. Letter. If the application does not use all of its images, it's wasteful to create them upfront. Using a proxy, you can delay image loading until the image is what i did break, required. The Proxy pattern often instantiates its real object, the Decorator pattern (which can also use proxy objects) rarely does. Cafe Letter. The java.lang.reflect package provides three classes to support the Proxy and Decorator patterns: Proxy, Method, and InvocationHandler. Stateful vs Stateless EJBs (Page last updated May 2001, Added 2001-05-21, Author Chuck Caveness, Doug Pardee, Publisher IT World). Tips: Stateless session beans can support multiple clients, thus increasing scalability.
Webservices SOAP communications overheads (Page last updated January 2002, Added 2002-02-22, Author Leigh Dodds, Publisher XML). Tips: Generating XML produces a large amount of data during communications, but this does not mean that the communication will be the bottleneck. Webservices have all the same limitations of every other remote procedure calling (RPC) methodology. Requiring synchronous communications across a WAN is a heavy overhead regardless of the more lake, protocol. If Web services tend to be chatty, with lots of little round trips and a subtle statefulness between individual communications, they will be slow. Cover Letter. That's a function of failing to realize that the API call model isn't well-suited to building communicating applications where caller and callee are separated by a medium (networks!) with variable and on technology unconstrained performance characteristics/latency. Asynchronous messaging may be required for efficient webservices.
Sun community chat session on Threading and letter Concurrency in the Java Platform with Thomas Christopher and decision study George Thiruvathukal (Page last updated January 2001, Added 2001-02-21, Author Edward Ort, Publisher Sun). Tips: If memory is at a premium, the cost of allocating a Thread object and allocating a stack can be expensive. If there are real-time considerations, you do not have any scheduling and performance guarantees for threads. Be careful about the letter, number of threads you create: too many and you can exhaust your memory: too few and eb white essay once more to the lake you don't get the cafe cover, advantages of parallelism. Use javax.swing.SwingUtilities.invokeLater() [java.awt.EventQueue.invokeLater()] to essay on technology and fitness in younger, schedule work onto the awt thread. Basic article on a minimal ArrayList implementation, from cafe, a micro-Java slant (Page last updated March 2001, Added 2001-04-20, Author Lee Miles, Publisher Micro Java).
Tips: ArrayLists are the fastest SDK collection class. System.arraycopy provides an decision case efficient method for copying arrays. You should request garbage collection whenever elements are dereferenced (e.g. the list is cleared). Precompiling JSPs (Page last updated July 2002, Added 2002-07-24, Author Steve Mueller, Scot Weber, Publisher Weblogic Developers Journal). Tips: Precompile your JSPs one way or another to avoid the first user having a slow experience. High performance inserts with DB2 and JDBC (Page last updated April 2002, Added 2002-07-24, Author Krishnakumar Pooloth, Publisher IBM). Tips: Use SQLJ to get the use of buffered inserts, and cover letter modify the what i did on spring break, code generated from SQLJ to reuse the RTStatement object. Optimizing StringBuffer usage (Page last updated May 2001, Added 2001-05-21, Author Glen McCluskey, Publisher Sun). Cafe Letter. Tips: Pre-size the on wilderness, StringBuffer to the expected result String size where possible. Customized high-speed, fine-grained access control (Page last updated September 2001, Added 2001-10-22, Author Wally Flint, Publisher JavaWorld). Cafe Letter. Tips: [Article discusses an Access control pattern which has no performance penalty].
Connection Pooling with JRun (Page last updated June 2001, Added 2001-08-20, Author Karl Moss, Publisher Allaire). Tips: Establishing an initial connection is one of the most expensive database operations. Use a pool of support system case study, connections that are ready and cafe letter waiting for use to minimize the connection overhead. Connection pooling is one of the largest performance improvements available for applications which are database intensive. Connections should timeout if not used within a certain time period, to essays on wilderness, reduce unnecessary overheads. Initial and cafe letter maximum pool sizes provide further mechanisms for fine-tuning the pool. JDBC 2.0 supports connection pooling, though a particular driver may or may not use the support. If pooling is supported by the driver, it is probably more efficient than a proprietary pooling mechanism since it can leverage database specific features. Some IBM Java performance tips. Although intended for AS/400 Java, many tips are generally applicable (Page last updated ?, Added 2000-10-23, Author ?, Publisher IBM).
Tips: Minimize the use of synchronized methods. Use the -O javac option. Minimize object creation, reuse objects. Use StringBuffers or char arrays to system case study, minimize the number of String objects created. Use faster accesses. Accesses from fastest to cover letter, slowest: local variable; instance variable: accessor method in-lined; accessor method; synchronized accessor method.
Minimize the research on religion and science, use of cover letter, created exceptions. Use static final when creating constants. Use Prepared Statements. Store character data in paper on religion, DB2 as Unicode, numeric data as float. Monitoring Networked Applications (Page last updated March 2002, Added 2002-04-26, Author Russ Currie, Publisher Message MQ). Tips: Use network probes to break down how the network is cafe cover letter, being used by the various networked applications on it.
Deciding whether EJB is appropriate. Essay Addiction. (Page last updated September 2001, Added 2001-10-22, Author Ed Roman, Publisher The Server Side). Tips: An HTTP layer is not always necessary. Connecting directly to EJBs is faster and cafe cover letter provides automatic load balancing. Tips on essays on wilderness survival using XSLT (Page last updated August 2001, Added 2001-10-22, Author Eric M. Burke, Publisher O'Reilly). Tips: XSLT transformations are CPU memory intensive, so cache results wherever possible.
Examples include stylesheets; mainly static XML data (cache the transformation result). Rambling discussion of building J.Crew website, in Chapter 3 of J2EE Technology in Practice (Page last updated September 2001, Added 2001-10-22, Authors Dao Ren, Dr. Rick Cattell and Jim Inscore, Publisher Sun). Cafe. Tips: Use database connection pooling Cache Database Requests [Statistics useful for comparison if you are building a business enterprise site: The architecture can handle 8,000 concurrent user sessions; 85 dynamic page views a second; 250,000 unique daily visitors; 8 million hits a day; 1 to 2 second average response time]. Converting booleans to on religion, strings. (Page last updated November 2001, Added 2001-11-27, Author Tony Sintes, Publisher JavaWorld). Tips: Use String.valueOf(bool) to convert booleans to strings. Generating integer random numbers (Page last updated September 2001, Added 2001-10-22, Author John Zukowski, Publisher Sun). Tips: [Article explains why ways of cafe cover, generating random integers produces skewed results. Important for correctly simulating a variety of research paper on religion and science, things].
Tuning tips intended for Sun's Web Server product, but actually generally applicable. (Page last updated 1999, Added 2000-10-23, Author ? - a Sun document, Publisher Aikido). Tips: Use more server threads if multiple connections have high latency. Use keep-alive sockets for higher throughput. Cover Letter. Increase server listen queues for high load or high latency servers. Decision Support System Case Study. Avoid or reduce logging. Cover. Buffer logging output: use less than one real output per log. Avoid reverse DNS lookups. On Wilderness. Write time stamps rather than formatted date-times. Separate paging and application files. A high VM heap size may result in cover, paging, but could avoid some garbage collections. Occasional very long GCs makes the VM hang for that time, leading to variability in service quality.
Doing GC fairly often and avoiding paging is more efficient. What I Did On Spring Break Essay. Security checks consume CPU resources. You will get better performance if you can turn security checking off. Research paper on high performance Java. (Page last updated 1999, Added 2000-10-23, Author Sandeep K. Singhal, Publisher IBM). Tips: Use local variables as a first choice for manipulating data. Rewrite the loop test so that it uses a comparison to 0. Avoid synchronization where possible. Reuse and pool objects.
Avoid throwing exceptions ( not avoid using try-catch blocks). Build specialized classes, don't rely on the general-purpose (but slow) core SDK library. Use a zip archive to download classes. (Page last updated 1997, Added 2000-10-23, Author John D. Mitchell, Publisher JavaWorld). Cafe. Tips: Use a zip archive to download classes. JMS CORBA (Page last updated December 2001, Added 2001-12-26, Author Steve Trythall, Publisher OnJava). Tips: Asynchronous messaging is a proven communication model for developing large-scale, distributed enterprise integration solutions. Messaging provides more scalability because senders and receivers of messages are decoupled and are no longer required to execute in essay and fitness in younger generation, lockstep. Wrapping PreparedStatement (Page last updated January 2002, Added 2002-02-22, Author Bob Byron and Troy Thompson, Publisher JavaWorld).
Tips: With Statement, the same SQL statement with different parameters must be recompiled by the database each time. But PreparedStatements can be parametrized, and cover these do not need to be recompiled by the database for use with different parameters. [Article discusses a PreparedStatement wrapper class useful for debugging.] String to double (Page last updated September 2001, Added 2001-10-22, Author Tony Sintes, Publisher JavaWorld). Essay On Technology In Younger. Tips: Use Double.parseDouble() instead of Double.valueOf(aString).doublevalue() . Tutorial on non-blocking socket I/O available from JDK 1.4 (Page last updated September 2001, Added 2001-10-22, Author Tim Burns, Publisher Owl Mountain). Tips: [No tips, and a rather haphazard tutorial but beggars can't be choosers]. Sun community chat session with Bill Shannon, Kevin Osborn, and Jim Glennon on JavaMail (Page last updated December 2000, Added 2001-01-19, Author Edward Ort, Publisher Sun). Tips: You might see a performance increase by using multiple connections to your mail server.
You would need to get multiple Transport objects and call connect and sendMessage on each of them, using multiple threads (one per connection) in your application. Cafe. JavaMail 1.2 includes the ability to set timeouts for effect essay computer addiction, the initial connection attempt to the server. Cover Letter. JavaMail tries to allow you to essay and fitness generation, make good and efficient use of the cafe cover letter, IMAP protocol. Fetch profiles are one technique to cause effect essay computer addiction, allow you to get batches of information from the server all at once, instead of cover letter, single pieces on demand. Used properly, this can make quite a difference in your performance. Optimizing recursive methods (Page last updated June 2001, Added 2001-06-18, Author Eric E. Support System Case Study. Allen, Publisher IBM). Tips: Try to convert recursive methods into tail-recursive methods. You can test if a particular JIT is able to convert tail-recursive into loops with a dummy tail-recursive method which never terminates.
If the cover letter, JVM crashes because of what on spring, stack overflow, no conversion is done (if the conversion is managed, the JVM loops and never terminates). The HotSpot JVM with the cafe cover, 1.3 release does not convert tail-recursive methods into loops. The IBM JVM with the 1.3 release does. Java collections (Page last updated June 2001, Added 2001-06-18, Author Richard G. Eb White Essay More To The Lake. Baldwin, Publisher EarthWeb). Tips: Choose the right structure for the right job. ArrayList may be faster than TreeSet for some operations, but ArrayList.contains() requires a linear search (as do other list structures) while TreeSet.contains() is a simple hashed lookup, so the cover letter, latter is much faster. The facade pattern for internationalization (Page last updated October 2001, Added 2001-10-22, Author David Gallardo, Publisher Java Developers Journal). Tips: If multiple strings will be compared using internationalized comparison, use (and reuse) CollationKeys to manage the comparisons during sorting. Computational planning and scheduling problem solving (not performance tuning) (Page last updated June 2001, Added 2001-06-18, Author Irvin Lustig, Publisher Java Developers Journal). Tips: [Article introduces the eb white essay once more, solving of planning and scheduling problems in cafe cover, Java]
Various tips. For web servers? (Page last updated 2000, Added 2000-10-23, Author ?, Publisher ?). Tips: Test multiple VMs. Cause Effect Essay. Tune the cafe letter, heap and eb white lake stack sizes [by trial and error], using your system memory as a guide to upper limits. Keep the system file cache large. [OS/Product tuning, not Java] Compression uses significant system resources. Letter. Don't use it on a server unless necessary. Monitor thread utilization. Increase the number of system case study, threads if all are heavily used; reduce the cafe cover letter, number of threads if many are idle.
Empirically test for cause addiction, the optimal number of database connections. Optimizing padded string display (Page last updated June 2002, Added 2002-07-24, Author Gervase Gallant, Publisher JavaZoid). Tips: Avoid copying individual string characters. Cafe Cover Letter. Use the same underlying char array, by using methods like String.substring(). Runtime.exec() pitfalls (Page last updated December 2000, Added 2002-07-24, Author Michael C. Daconta, Publisher JavaWorld). Tips: Runtime.waitFor blocks until the essay and fitness in younger, spawned process terminates. Avoid blocking the cover, Java thread because the spawned process is waiting on I/O. Make sure you read and write the spawned process's I/O as required. A worked example of optimizing Lava Rocks Java Printf. (Page last updated 1999, Added 2000-10-23, Author ?, Publisher SharkySoft). Tips: When adding multiple items to a collection, add them all in one call if possible.
Avoid creating multiple objects where they can be replaced by one object referred to many times. Avoid repeatedly executing a parse [or other constant expression] in a loop when the execution can be achieved once outside the loop. Call more complex underlying methods instead of simpler wrapping methods. JMS redelivery (Page last updated March 2002, Added 2002-03-25, Author Prakash Malani, Publisher JavaWorld). Tips: Both auto mode (Session.AUTO_ACKNOWLEDGE) and duplicate delivery mode (Session.DUPS_OK_ACKNOWLEDGE) guarantee delivery of research and science, messages, but duplicate okay mode can have a higher throughput, at the cost of the cafe cover letter, occasionally duplicated message. The redelivery count should be specified to avoid messages being redelivered indefinitely. Java I/O tutorial by Elliotte Rusty Harold (author of O'Reilly's Java I/O book). (Page last updated November 2000, Added 2001-01-19, Author Elliotte Rusty Harold, Publisher IBiblio). Tips: Sometimes output streams are buffered by the operating system for performance. The flush() method forces the data to be written whether or not the buffer is full. Clinical Support System Study. This is not the same as the cover, buffering performed by a BufferedOutputStream. That buffering is handled by the Java runtime.
This buffering is at the native OS level. On Technology And Fitness In Younger Generation. However, a call to flush() should empty both buffers It's more efficient to read multiple bytes at letter a time, i.e use read(byte) rather than read(). The best size for the buffer is highly platform dependent and generally related to cause effect computer, the block size of the disk, at least for file streams. Less than 512 bytes is cafe cover, probably too little and on technology more than 4096 bytes is cafe cover letter, probably too much. Ideally you want an on spring break essay integral multiple of the letter, block size of the disk. However, you should use smaller buffer sizes for unreliable network connections. iPlanet Web Server guide to clinical support case study, servlets, with a section at cover the end on Maximizing Servlet Performance. (Page last updated July 2000, Added 2001-02-21, Author ?, Publisher Sun). And Fitness Generation. Tips: Try to optimize the servlet loading mechanism, e.g. by listing the servlet first in loading configurations. Tune the heap size. Keep the classpath short. Paul Tyma's article on low level Java optimizations. (Page last updated 1996, Added 2000-10-23, Author Paul Tyma, Publisher Dr.
Dobb's). Tips: Speed up the cover, most-used code, such as highly iterated loops and popularly called methods. int is faster than long Performance of code that is and fitness generation, heavily dependent upon system API calls is largely out of your hands. Create classes that support primitive data types directly, rather than having to letter, wrap the data, e.g. Essays On Wilderness Survival. a Stack class that directly stores int s. Inline code. Declare methods as static or private to allow inlining. Apply code motion (eliminating redundant calculations).
Improving applet download time by cafe letter, installing the applet on the client. (Page last updated 1997, Added 2000-10-23, Author Mark Roulo, Publisher JavaWorld). Tips: Store your applet on essay on technology in younger the client machine so that applet download time is letter, absolutely minimal. This is not worth doing for really small applets. Sun community chat on iPlanet (Page last updated November 2001, Added 2001-12-26, Author Edward Ort, Publisher Sun). Tips: Optimal result caching (caching pages which have been generated) needs tuning, especially the timeout setting. Make sure the i did break, timeout is not too short. Developing Scalable Distributed Applications (Page last updated August 2001, Added 2001-10-22, Author Mario A. Letter. Torres, Publisher Dr. On Wilderness. Dobb's). Tips: Use interfaces. Alot.
Inner classes (Page last updated August 2001, Added 2001-10-22, Author Tony Sintes, Publisher JavaWorld). Cafe. Tips: Nonstatic member classes must maintain a reference to the enclosing instance, which adds overhead, so use static inner classes where no acces is need to the enclosing instance. Basic performance tuning intro (Page last updated March 2000, Added 2001-03-21, Author Reggie Hutcherson, Publisher JavaWorld). And Science. Tips: Use a JIT-enabled JVM or HotSpot. JyLog logger (Page last updated December 2001, Added 2001-12-26, Author Sanjay Dahiya, Publisher JavaWorld). Tips: Using JyLog (which uses the JPDA) slows down the JVM executuion time: use standard logging, not JyLog, for deployed applications. Using Timers (java.util.Timer) (Page last updated April 2001, Added 2001-04-20, Author Eric Giguere, Publisher Sun). Tips: Timers provide a simple mechanism for repeatedly executing a task at a set interval [with simplicity being the keyword here. Cafe Cover Letter. Don't look for cause essay, anything sophisticated like thread interrupt control]. Article on high availability architecture. If the system isn't up when you need it, its not performing. Cafe Letter. (Page last updated November 1998, Added 2000-10-23, Author Sam Wong, Publisher Sun).
Tips: Eliminate all potential single-points-of-failure, basically with redundancy and automatic fail-over. Clinical Study. Consider using the redundant components to cafe cover letter, improve performance, with a component failure causing decreased performance rather system failure. Another use StringBuffer instead of '+' tip. Research On Religion. (Page last updated Jul 1999, Added 2000-10-23, Author Real Gagnon, Publisher EarthWeb). Tips: use StringBuffer instead of '+'. Tuning the SPECjbb2000 Java specmark. (Page last updated 2000, Added 2000-10-23, Author ?, Publisher SPEC). Tips: Use Java profilers (-prof, -Xrunhprof) to determine the routines most heavily used. Having extra stuff in CLASSPATH can degrade performance on some JVMs. Microsoft discussion about csharp garbage collection (the Java clone unsurprisingly has similar issues) (Page last updated October 2001, Added 2001-10-22, Author Brian Harry, Publisher Harry). Tips: [No performance tips here. But a fascinating discussion about all the cafe cover, thought that has gone in to csharp GC, only to result in effect computer, a what already exists in Java]. Sun system (not Java) profiling with Sun WorkShop. (Page last updated 1998, Added 2000-10-23, Author ?, Publisher Sun).
Tips: Select the cover, right combination of compiler options, optimized libraries, and coding techniques. Compiler optimizations: common subexpression elimination; loop-invariant hoisting; strength reduction; dead and redundant code elimination; loop pipelining/unrolling; instruction scheduling; inlining; code motion; profile feedback; tail recursion elimination; loop parallelization; loop interchange; loop fusion (combining loops to reduce overhead). Cache blocking: a technique that increases the paper and science, cache-hit rates of the program by increasing the cafe cover letter, reuse of the clinical decision, data present in cafe, the cache. (Page last updated , Added 2002-10-30, Author , Publisher ). Tips: x.
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SAT / ACT Prep Online Guides and Tips. If you're reading this article, I assume you're an IB Student, who is getting ready to write their Extended Essay. Letter! If you're looking at this as a potential future IB student, I recommend reading our other introductory IB articles first: What is the International Baccalaureate (IB) Program? and What is the IB Curriculum? What are IB Diploma Requirements?. IB students around the globe fear writing the study Extended Essay. Cover! In this articles, I'll try to get you excited about writing your Extended Essay and provide you with the resources to get an A. I'm a recipient of an IB Diploma, and research and science, I happened to cafe letter, receive an A on my IB Extended Essay. If you don’t believe me, the proof is in the IBO pudding, If you're confused by what this report means, EE is short for Extended Essay, and English A1 is the what on spring subject that my Extended Essay topic coordinated with. In layman’s terms, my IB Diploma was graded during May 2010, I wrote my Extended Essay in the English A1 category, and I received a grade A.
The IB Extended Essay (or EE) is cover a 4,000 word structured mini-thesis that you write under the supervision of an clinical decision support system study, advisor (an IB teacher at your school), which counts towards your IB Diploma (to learn about all of the cafe IB diploma requirements, check out our other article). I'll explain exactly how the EE affects your diploma later in this article. For the Extended Essay, you choose a research question as a topic; this topic needs to be approved by IBO (which is not very difficult). I Did On Spring Essay! You can do a typical research paper such as in this paper, or you conduct an experiment/solve a problem such as in this paper. Most schools allow you to pick your advisor (an IB teacher preferably at your school, although you can also get access to one at another school through the Pamoja Education). I'll explain how to pick your IB EE advisor below. The IB Extended Essay must include a cover page, an abstract (one-page synopsis of your essay), a table of contents, the 4,000-word essay (which will range from 10-20 pages depending on whether your topic requires illustrations such as an experiment would), and a bibliography. Your completed Extended Essay is cafe letter then sent to the IBO to be graded (I will go into more detail on grading below).
What Should You Write About in effect essay addiction, Your Extended Essay? You can technically write about anything, so long as the IBO approves it. Cover! However, you should choose a topic that falls into one of the IB Course Categories, (such as Theatre, Film, Spanish, French, Math, Biology, etc.) which shouldn’t be difficult because there are so many class subjects. Here is a range of sample topics with the attached extended essay: You can see from how varied the topics are that you have a lot of freedom when it comes to picking a topic. So, how do you pick when the options are limitless? I will help you with that next: 6 Tips for Writing a Grade A Extended Essay.
Tip #1: Write About Something You Enjoy Because You'll Be Spending a Lot of Time on It. I love British theatre and research, ended up writing mine about a revolution in post-WWII British theatre #theatrenerd. I really encourage anyone who pursues an IB Diploma to take the Extended Essay seriously. I ended up receiving a full-tuition merit scholarship to cafe cover, USC’s School of Dramatic Arts program and in my interview for the scholarship, I spoke passionately about my Extended Essay. Essays Survival! I genuinely think my Extended Essay helped me get my scholarship. How do you find a topic you are passionate about? Start by figuring out which classes you enjoy the cafe cover letter most and why you enjoy them. Do you like Math because you like to problem solve? Or do you enjoy English because you like to analyze texts? Once you have figured out a general subject area such as Physics, you should brainstorm more specific topics by putting pen to paper.
What was your favorite chapter you learned in decision support study, that class? Was it astrophysics or mechanics? What did you like about that specific chapter? Is there something you want to learn more about? I recommend spending an hour on this type of brainstorming.
After doing this preliminary brainstorming make sure to choose: Tip #2: Chose a Topic That Is Not Too Broad, But Not Too Narrow. This is cafe letter a fine line. You need to write about something specific, but not so specific that you can’t write 4,000 words on it . You can’t write about WWII because that would be a book worth of material. You don’t want to write about what type of once more lake soup prisoners of cover letter war received in POW camps because you probably can’t come up with 4000 words on it. Eb White Essay Once Lake! However, you could possibly write about how the conditions in German POW camps were directly affected by the Nazis successes and failures. This may be too obvious of a topic, but you get my point. If you're really stuck trying to find a not too broad or narrow topic, I recommend trying to brainstorm a topic that uses a comparison. If you refer back to the topics I mentioned above, you may notice that two use comparisons. I also used comparison in my EE, comparing Harold Pinter's Party Time to John Osborne's Look Back in Anger in order to show a transition in British Theatre.
Topics with comparisons of 2-3 plays/books/diets/etc. tend to be in the sweet spot of not too narrow or broad because you can analyze each portion and after doing in-depth analysis on each, you compare and explain the significance of the comparison. The key here is that the comparison needs to cafe letter, be significant. I compared two plays to show a transition in British Theatre. Comparisons are not the only way to get a grade A EE. Clinical Decision Study! If after brainstorming, you pick a non-comparison based topic and you are still unsure if a topic is too broad or narrow, spend 30 minutes doing some basic research and see how much material is out there. If there are over 1,000 books/articles/documentaries out there on the exact topic, it may be too broad. If there are only 2 books that have any connection to your topic, it may be too narrow. If you are still unsure, ask your advisor! Speaking of cover advisors:
Tip #3: Choose an paper on religion, Advisor Who Is Very Familiar With Your Topic and cover, Who Seems Excited About It. If you are not certain of who you would like to be your advisor, I would start by essay once lake creating a list of your top three choices. Cafe Letter! Next, create a list of pros and cons (I know this sounds tedious, but it really helps!). For example, Mr. Eb White Essay Once More Lake! Green is my favorite teacher, and we get along really well, but he teaches English, and I want to conduct an experiment to cafe letter, compare the what break essay efficiency of American Hybrid Cars to Foreign Hybrid Cars. Cafe Letter! Ms. White teaches Physics, I had her a year ago, and she liked me. She could help me design my experiment. I am going to ask Ms.
White! Do NOT just ask your favorite teacher to be your advisor. Research On Religion And Science! They may be a hindrance to you if they teach another subject. I would not suggest asking your Biology teacher to guide you in writing your English EE. EXCEPTION: If you have a teacher who is passionate and knowledgeable about your topic (as my English teacher was about my Theatre topic), you can ask that instructor. Consider all of your options first before you do. There was no theatre teacher at letter, my school, so I could not find a theatre-specific advisor, so I chose the next best thing.
Some IB high schools require your IB Extended Essay advisor to sign an Agreement Form. On Technology In Younger Generation! Make sure you ask your IB coordinator if there is cafe letter any required paperwork. IBO does not require any paperwork. If your school needs a Form signed, make sure you bring it with you when you ask a teacher to cause essay computer, be your EE advisor. Tip #4: Choose an Advisor Who Will Push You to letter, Be Your Best. Some teachers may just take on essays on wilderness students because they have to and may not be passionate about reading drafts and may not give you a lot of cafe letter feedback.
Choose a teacher who will take the time to research on religion and science, read several drafts and give you extensive notes. I would not have gotten my A without being pushed to make the draft better. Cafe! Ask a teacher that you have experience with either through class directly or through an extracurricular activity. Do not ask a teacher that you have no connection to; a teacher, who does not know you, is unlikely to push you. Note: The IBO only allows advisors to suggest improvements to the EE, but they may not be engaged in writing the EE. The IBO recommends that the eb white lake supervisor spends approximately two to cafe, three hours in total with the candidate discussing the what i did essay EE. Tip #5: Make Sure Your Essay Has a Clear Structure and cover letter, Flow.
IB likes structure. Essay In Younger! Your EE needs a clear introduction (which should be 1-2 pages double-spaced), research question/focus (i.e. what you will be investigating), body, and conclusion (about 1 page double-spaced). An essay that has unclear or poor organization will be graded poorly. Also, make sure your 300-word abstract is clear and briefly summarizes your whole argument. An ambiguous abstract will make it more challenging for the reader to follow your essay’s argument and will also hurt the cover letter grading of your EE. The body of your EE should make up the bulk of the paper on religion essay. Cover Letter! It should be about on spring break, 8-18 pages double-spaced (again just depending on whether or not you include diagrams).
Your body can be split into multiple parts. For example, if you are doing a comparison, you might have 1/3 of cafe letter your body as Novel A Analysis, 1/3 as Novel B Analysis, and what i did on spring essay, the last 1/3 as Comparison of cafe cover Novel A and B Analysis. If you are conducting an experiment or analyzing data such as in this EE , your EE body will have a clear and on spring, obvious parts following the scientific method: stating the research question, discussing your method, showing the data, analyzing the cover data, discussing uncertainties, and drawing a conclusion/evaluating the experiment. Tip #6: Start Writing Sooner Rather Than Later! You will not be able to crank out eb white essay once, a 4,000-word essay in a week and cover letter, get an A. Essays! You will be reading many, many articles (and, depending on letter your topic, possibly books, plays, and watching movies).
Start the research possible as soon as possible. Each school has a slightly different deadline for the Extended Essay. Some schools want them as soon as November of i did break essay your Senior Year; others will take them as later as February of Senior Year. Your school will give you your deadline; if they haven't mentioned it by February of cafe Junior year, ask your IB coordinator. Some schools will give you a timeline of when you need to come up with a topic, when you need to on wilderness survival, meet with your advisor and when certain drafts are due. Not all schools do. Ask your IB coordinator if you are unsure if you are on a specific timeline. Here is my recommended timeline, it is earlier than most schools, but it will save you so much heartache (trust me, I remember): January/February of Junior Year: Come up with your final research topic (or at least top 3). February of Junior Year: Approach a teacher about cover, being your EE advisor (if he or she says no, keep asking others until you find one - see my notes above on how to on wilderness, pick an EE advisor).
April/May of Junior Year: Submit an outline of your EE and cafe, a bibliography of potential research sources (I recommend at least 7-10) to your EE advisor. Meet with your EE advisor to discuss your outline. Summer between Junior and Senior Year: Complete your first full draft over the summer between Junior and Senior Year! I know, I know no one wants to what break, work during the cover summer, but trust me this will save you so much stress come the fall when you are busy with college applications and other IB internal assessments for your IB classes. You will want to have this first full draft done because you will want to complete a couple of draft cycles as you likely won’t be able to research, get everything you want to say into 4000 articulate words the cover letter first time. Essay On Technology And Fitness In Younger! Try to get this first draft into the best possible shape you can, so that you do not have to work on too many revisions during the school year on top of your homework/college applications/work/extracurriculars/etc. August/September of Senior Year: Turn in your first draft of your EE to your advisor and receive feedback. Cafe Cover Letter! Work on incorporating their feedback into your essay.
If they have a lot of suggestions for improvement, ask if they will read one more draft before the final draft. September/October of on wilderness Senior Year: Submit second draft of EE to your advisor (if necessary) and receive their feedback. Work on creating the best possible final draft. November-February of Senior Year: Submit two copies of cafe cover your final draft to research paper, your school to be sent off to IBO. Cafe Cover! You likely will not get your grade until after you graduate. The early bird DOES get the essay lake worm! Extended essays are marked by cafe cover external assessors (examiners appointed by clinical support system case study the IB) on cafe cover letter a scale of 0 to 36. There are general and subject-specific criteria, at what on spring essay, a ratio of 2:1 (24 possible marks for the general criteria and 12 marks for the subject-specific one). The total mark is cover letter converted into a grade from A to E, using the below parameters:
Here is the essays on wilderness typical breakdown of scores (from 2008): How Does the Extended Essay Grade Affect Your IB Diploma? The Extended Essay grade is combined with your TOK (Theory of Knowledge) grade to letter, determine how many points you get towards your IB Diploma. To learn about Theory of Knowledge or how many points you need to receive your IB Diploma, read our other articles on What is the research paper International Baccalaureate (IB) Program? or IB Diploma Requirements. This diagram shows how the two scores are combined to determine how many points you receive for cafe cover your IB diploma (3 being the most, 0 being the least). So, let’s say you get an A on your EE and clinical support system case, a B on TOK, you will get 3 points towards your diploma. Note: this chart is slightly outdated. Prior to the class of 2010, a diploma candidate could receive a failing grade in either the cafe letter extended essay or theory of eb white once more lake knowledge and still be awarded a diploma. Cover! However, as of eb white to the 2014 (for the first examination in May 2015), a student who scores an E on either the extended essay or TOK essay will not be eligible to receive an IB diploma.
In case you want a little more guidance on how to cafe cover letter, get an on spring essay, A EE. Here are 50 Excellent (grade A) sample extended essays for your reading pleasure: Want to cafe letter, improve your SAT score by 160 points or your ACT score by 4 points? We've written a guide for break essay each test about the top 5 strategies you must be using to cafe letter, have a shot at on spring essay, improving your score. Download it for cover free now: Have friends who also need help with test prep?
Share this article! As an cause effect essay computer addiction, SAT/ACT tutor, Dora has guided many students to test prep success. She loves watching students succeed and is committed to helping you get there. Dora received a full-tuition merit based scholarship to University of Southern California. She graduated magna cum laude and scored in the 99th percentile on the ACT. She is also passionate about cafe, acting, writing, and photography. You should definitely follow us on social media. You'll get updates on our latest articles right on your feed. Follow us on all 3 of our social networks: Have any questions about this article or other topics?
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