Gatling is a framework for performance testing and Apache James contributors had been providing a DSL (Domain Specific Language) for easily writing IMAP performance tests. We also wrote JMAP benchmarks using Gatling.

This talk will cover the inner working of Gatling, the architecture of the IMAP DSL, key contributions to Yahoo's imapnio library, the toolbox for performance testing Apache James (including provisionning data), and present related results.

We will also present how it completes other performance-related tools of the Apache James eco-system: Grafana metrics, async-profiler flame graphs (and contributions to the FOSS eco-system it did lead to!), JMH (Java Micro-benchmark Harness) tests for MIME4J...