jfrunit VS async-profiler

I haven't had chance to use it properly yet, but I think JfrUnit[0][1] is a good option here to test non-functional behaviour like memory usage and garbage collection.

[0]: https://github.com/moditect/jfrunit

JfrUnit: Allows to assert JFR events in JUnit tests (details)

I do not know of any library that would particularly help here, except maybe this thingie might help with writing tests to assert your expected behaviour holds: https://github.com/gunnarmorling/jfrunit (A potentially relevant example here: https://twitter.com/gunnarmorling/status/1335326054496555008). However, there's no public release as of yet.

Using the Async Profiler we were able to build flamegraphs for the first and second queries to picture the differences in path length of the two transactions execution.

> The other two languages I’ve used mostly in recent decades are Java and Ruby and the profiler situation is for both those languages is kind of shitty. I had to pay real money to get the Java profiler I used at AWS and while it worked, it was klunky, not fun to use.

These days, async profiler (https://github.com/jvm-profiling-tools/async-profiler) is much better than the Go tooling for performance. It is a joy to use and features a top-like view for the hottest methods. It works for locks, allocations and CPU time. It also integrates with JMH.

Also, running it under a profiler (I recommend async-profiler[1]) should give you a good idea of where the slowdown occurs which might help you pin it down further.

[1] https://github.com/jvm-profiling-tools/async-profiler

Profile it. async-profiler is really great. Alternatively you can check out VisualVM/JProfiler/YourKit

async-profiler is really great at analyzing allocations, give it a shot!

JFR to Flame Graph Converter

Async Profiler converter tool does support JFR to Flame Graph, JFR to FlameScope, collapsed stacks to Flame Graph -https://github.com/jvm-profiling-tools/async-profiler#download