Web Performance Matters

Do you subscribe to email newsletters? If you're like me, you get lots of them. New ones appear in my inbox every morning. They pile up, demanding to be read. In fact, they seem to breed like rabbits, producing new offspring -- when did I express an interest in Enterprise VOIP Security Architecture issues? Sometimes in a housekeeping splurge I delete a few dozen at once, suffering a momentary twinge of anxiety at having perhaps missed something important. So usually I skim them before hitting the delete button.

TechTarget's Search Software Quality service seems to be especially prolific, but is also a regular source of interesting references -- like TheServerSide.com, the subject of a recent note. According to the site's home page:

Java Performance Management for Large-Scale Systems

There are many classes of enterprise applications that have stringent performance and scalability requirements. TheServerSide.com has assembled a collection of resources to help you better design, develop, test and manage high performance, large-scale systems - learn new and innovative approaches for performance tuning, memory management, concurrent programming, JVM clustering and more.

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Managing Response Time for Web Sites and Web Applications

Human beings don’t like to wait. We don’t like waiting in line at a store, we don’t like waiting for our food at a restaurant, and we definitely don’t like waiting for Web pages to load.

Those words open Web Page Response Time 101, an excellent article by Alberto Savoia. Although it was published in July 2001, it remains every bit as relevant and useful today. It does a really good job of explaining and summarizing two fundamental aspects of Web performance -- human behavior and site behavior.

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Clustering and distributing Java applications has never been easier than it is today. As a result, writing good distributed performance tests and tuning those applications is increasingly important. Performance tuning and testing of distributed and/or clustered applications is an important skill and many who do it can use a little help.

That paragraph introduces a new series of four posts about how to approach testing for distributed Java applications by Steve Harris of Terracotta, who blogs as DSO Guy. Steve frames his guidelines as anti-patterns -- in other words, pitfalls or "commonly-reinvented bad solutions to problems" to be avoided [see Wikipedia].

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Response Time Standards for Web Sites and Web Applications

It feels like hardly a single day has passed in the past six years that someone hasn't asked me this questions: "What is the industry standard response time for a Web page?" And in the past six years, the answer hasn't changed, not even a little bit. So if the answer hasn't changed, why am I still getting asked the question on virtually a daily basis?

That is a quote from Acceptable application response times vs. industry standard, an article by Scott Barber published by TechTarget on March 13, 2007.

As I read Scott's article, I found myself in strong agreement with every point. By the end, I realized that Scott had echoed and summarised many previous posts of mine. So I have used Scott's words as a framework to collect together references to my previous articles on the subject of performance objectives -- what they should be, and how you should set them:

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Performance Management (SLM) Challenges for Web 2.0, Ajax, and Rich Internet Applications (RIA's)

Last week, TechTarget published an article by Patrick Lightbody about the performance of Web 2.0 applications. The article's technical core -- which I review below -- is a useful checklist of ten recommendations for developing and testing Web 2.0 applications with performance in mind.

For the full article, see Ten ways to improve testing, performance of Web 2.0 applications.

Because I believe in systematic performance engineering, I am always pleased when writers advocate proactive approaches to application performance. It's the only rational way to ensure acceptable performance in production applications. So it's too bad that Patrick feels the need to justify his good advice by surrounding it with an introduction and conclusion that suffers from all the worst features of Web 2.0 coverage. A few half-truths are buried in an amalgam of excessive hype, false claims, meaningless analysis, and an optimism that underestimates the real technical challenges.

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Your new Web application is almost ready to go live, but you need to be sure it will handle the projected traffic -- before that traffic hits the site. You probably already know that you can't just collect up your working test scripts and loop through them at high speed.

And just five minutes with Google should be enough to convince you that software performance testing is not a trivial matter.

So what should you do?

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Performance testing is the discipline concerned with determining and reporting the current performance of a software application under various parameters. But there comes a time after the tests are run when someone who's reviewing the results asks the deceptively simple question: So what, exactly, does all this mean? This point beyond performance testing is where the capabilities of the human brain come in handy.

With these words, Scott Barber introduced a series of articles on IBM's DeveloperWorks site about the human aspects of performance testing.

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Posts on The Importance of Measurements and Controlling Software Projects have reviewed the origin of the saying that "you can't manage what you can't (or don't) measure". Today I look more closely at its meaning and validity -- how true is it?

One apparent contradiction is that this much quoted fact of management is also widely viewed as a fallacy -- or at least, as an over-exaggerated claim -- especially by people in the software engineering profession, which seems (in the person of Tom DeMarco) to have coined the saying in the first place. That contradiction was highlighted in a 2003 book by Robert L. Glass, Facts and Fallacies of Software Engineering [Amazon].

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Previous posts in this series described the influence of Moore's Law and Wirth's Law on application performance, how to balance hardware capacity and software demand with a systematic approach to performance tuning, and the five fundamental elements of computer system performance.

This post is the second of a small group devoted to the importance of measurements. Kelvin's dictum ("if you cannot measure, then your knowledge is meagre and unsatisfactory"), and the popular saying, "you can't manage what you can't (or don't) measure," each advance the idea that measurements are indispensable.

But such a sweeping claim may not actually be true in every instance, so I am now highlighting some slightly more focused statements about the value of measurements.

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Previous posts in this series described the influence of Moore's Law and Wirth's Law on application performance, how to balance hardware capacity and software demand with a systematic approach to performance tuning, and the five fundamental elements of computer system performance.

Today's post is the first of several that will review insights on the central importance of measurements. Previously I've described how I view measurements as the foundation of all performance management -- see, for example, The ABC's of Measurement Data and my review of Practical Service Level Management.

Today's quote by Lord Kelvin sums up my point of view. Unless you have measured something, your attempts at managing it, and maintaining or improving its performance, will be unscientific at best ...

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