Load Testing

Load testing is the process of determining the system behavior under load. Ideally, we want to run load tests against an environment that closely matches our production environment. We might use a staging environment or a production build from our continuous integration pipeline.

For simplicity, we will run tests against a production version of our Phoenix application running on our development machine. This scenario is not ideal since the load tester itself will compete with the Phoenix application for machine resources but it is good enough to get started and build an expectation of the system behavior. At the end of this lesson, we’ll cover other tools that will provide better end-to-end testing.

Load testing with wrk

For this we’ll use wrk—an HTTP benchmarking and load testing tool. This can be found in most package managers. To get started, let’s start our Phoenix application in the production mode: