Java Flight Recorder

Java Flight Recorder (JFR) is a profiling and event-collection engine built directly into the JVM.

It records detailed runtime events — method samples, allocations, GC, locks, IO — to a binary .jfr file, with very low overhead. It ships with the JDK; no extra agent needed.

Traditional instrumenting profilers can slow an app by 2x or more, distorting the very timings you want.

JFR is designed to run in production with typically around 1% overhead. That means you can leave it on and capture a recording when a real incident happens, not just in a lab.