PerfJ is a wrapper of linux perf for java programs. As Brendan Gregg's words In order to profile java programs, you need a profiler that can sample stack traces. There has historically been two types of profilers: System profilers: like Linux perf, which shows system code paths (eg, JVM GC, syscalls, TCP), but not Java methods. JVM profilers: like hprof, LJP, and commercial profilers. These show J