RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v31]

[Johannes Bechberger]

On Tue, 3 Jun 2025 07:12:46 GMT, Johannes Bechberger <jbechberger at openjdk.org> wrote:

>> This is the code for the [JEP 509: CPU Time based profiling for JFR](https://openjdk.org/jeps/509).
>> 
>> Currently tested using [this test suite](https://github.com/parttimenerd/basic-profiler-tests). This runs profiles the [Renaissance](https://renaissance.dev/) benchmark with
>> - ... different heap sizes
>> - ... different GCs
>> - ... different samplers (the standard JFR and the new CPU Time Sampler and both)
>> - ... different JFR recording durations
>> - ... different chunk-sizes
>
> Johannes Bechberger has updated the pull request incrementally with three additional commits since the last revision:
> 
>  - Update src/hotspot/share/jfr/periodic/sampling/jfrCPUTimeThreadSampler.cpp
>    
>    Co-authored-by: Aleksey Shipilëv <shipilev at amazon.de>
>  - Update src/hotspot/share/jfr/periodic/sampling/jfrCPUTimeThreadSampler.cpp
>    
>    Co-authored-by: Aleksey Shipilëv <shipilev at amazon.de>
>  - Small fixes

We already do:


void JfrCPUTimeThreadSampler::on_javathread_terminate(JavaThread* thread) {
  JfrThreadLocal* tl = thread->jfr_thread_local();
  assert(tl != nullptr, "invariant");
  timer_t* timer = tl->cpu_timer();
  if (timer == nullptr) {
    return; // no timer was created for this thread
  }
  timer_delete(*timer);

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PR Comment: https://git.openjdk.org/jdk/pull/25302#issuecomment-2933945034