Summary

Collect test data throughout your system while testing. Knowing the behavior of as many components as possible helps you identify and resolve performance issues quickly. Also, look at the data you collect from a system perspective. Look for cause-and-effect relationships between the systems under test. If your application server suddenly goes quiet, look for a corresponding activity spike on another system indicating a bottleneck. Remember, the test environment (and the production web site it represents) acts as a system. Measure the entire environment rather than just the web components .

In the next chapter, we explore how to use the data you collect to find bottlenecks. We describe a series of common bottleneck symptoms and walk you through the analysis steps required to pinpoint the actual problem.