High Performance Drupal

Chapter 20. Load Testing

We mentioned in Chapter 1 that performance improvements are not a one-time task, but are something that should be revisited in iterations throughout the lifetime of a website. Load testing is an important aspect of any project: it provides insight into how your site and infrastructure will react under load. While critical to the launch process of any project, load testing is also useful to integrate into your standard testing procedure. It can help you locate bottlenecks and generic performance regressions introduced in the evolution of a site after launch (due to code and infrastructure changes).

There are many different methodologies and applications for performing load tests, but generally this testing involves accessing various pages on the site with enough traffic to start causing degradation. From there, work can be done to isolate bottlenecks in order to improve performance. If you perform periodic load tests, you are much more likely to catch something while it’s still a minor performance issue, not after it becomes a major problem.

Different Types of Load Tests

There are a number of different load testing configurations (sometimes referred to as test plans) that can be used individually or in conjunction to provide insight into site performance. Generally, we end up running three different types of tests:

Baseline tests

These tests are run with a relatively low amount of traffic in order to obtain some baseline information about site performance. ...