Testing Overview


Let's step back for a moment and consider what you want to accomplish with your test. Ultimately, you want to achieve the performance goals in the test plan. By reaching these goals, you demonstrate sufficient performance to support production traffic. Many test teams begin by enabling all the features and components of the web site, and running the performance test against them. We've never witnessed a successful test using this "all or nothing" strategy. Instead, we use a more systematic approach to testing.

First, start with a simple system. Begin testing and tuning a basic hardware configuration and add more components and features systematically. As you'll see in the section entitled Test Environment Configurations below, we recommend starting with the simplest form of your test environment possible: one HTTP server and a single application server instance interacting with minimal remote back-end systems.

Second, find the baseline of this simple system. How well does it perform now ? A surprising number of people start tuning without knowing where the system stands initially. Always find the throughput plateau and response time of the system before beginning the tuning process described in the next section. We cover how to do this in the Test Phases section of this chapter. Now you're ready to begin tuning if your system falls short of your performance goals. In the next section, we discuss the basic iterative process for tuning a system.

After you finish tuning your basic system, add other key parts of the web site, such as load balancers, to the test and tune them, using the performance of the simple system as a gauge. When you're satisfied with these components, it's time to begin scaling your system.

Remember, the key to a successful test is simplicity. Start with a simple system, tune it, and use this as a gauge as you increase the complexity of the test. Add components individually beyond the baseline and retest to determine their impact on performance. By adding components slowly and systematically, you quickly identify any performance problems introduced by these components and resolve them before moving on.

Whether your web site requires five application servers or fifty, the performance test always starts with the basics and walks toward the ultimate system. By resolving performance problems before adding the next level of complexity, you save time. This approach also allows you to collect capacity data for the basic components of the web site. The rest of this chapter covers our recommended test approach in more detail.



Performance Analysis for Java Web Sites
Performance Analysis for Javaв„ў Websites
ISBN: 0201844540
EAN: 2147483647
Year: 2001
Pages: 126

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