Professional Apache Tomcat 6

Chapter 20. Performance Testing

So far in this book, we have examined how to install, configure, and secure a distributed Tomcat environment. After expending the effort needed to install, configure, and tweak an installation, it is indeed a sad moment for a system administrator to see it all subverted because the application server buckles under a production load. Therefore, it is vital that administrators verify the performance characteristics of their Web applications before they are deployed for production use.

This chapter covers the concepts and processes of performance testing. By the end of the chapter, you will:

• Appreciate the importance of performance testing

• Understand how to develop a performance test plan

• Know how to use the Jakarta JMeter framework for performance testing and how to interpret the results

Performance Concepts

What does performance mean for a Web site? From a user's perspective, performance of a Web site boils down to how fast (or how slow) the Web pages load. However, as a Web site administrator, you need more precise ways to quantify the performance of your Web site.

What to Measure

There are two important properties that you should measure for quantifying the performance of your web site:

• Response time

• Throughput

The response time is the time it takes for one user to perform an operation. For example, in a storefront Web site, after the customer puts items in a shopping cart and clicks the Buy button, the time it takes to process the order and for the checkout ...