RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v29]
Markus Grönlund
mgronlun at openjdk.org
Mon Jun 2 15:04:12 UTC 2025
On Mon, 2 Jun 2025 13:50:49 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 one additional commit since the last revision:
>
> Fix bug related to async stack walking
src/hotspot/share/jfr/jfr.inline.hpp line 41:
> 39: inline void Jfr::check_and_process_sample_request(JavaThread* jt) {
> 40: JfrThreadLocal* tl = jt->jfr_thread_local();
> 41: bool has_cpu_time_sample_request = tl->has_cpu_time_jfr_requests();
Why this change?
src/hotspot/share/jfr/periodic/sampling/jfrCPUTimeThreadSampler.cpp line 191:
> 189: void sample_thread(JfrSampleRequest& request, void* ucontext, JavaThread* jt, JfrThreadLocal* tl);
> 190:
> 191: // process the queues for all threads that are in native state (and requested to be sampled)
"requested to be processed" I guess.
src/hotspot/share/jfr/periodic/sampling/jfrCPUTimeThreadSampler.cpp line 270:
> 268: void JfrCPUTimeThreadSampler::enroll() {
> 269: if (Atomic::cmpxchg(&_disenrolled, true, false)) {
> 270: log_info(jfr)("Enrolling CPU thread sampler");
log_trace, please.
src/hotspot/share/jfr/periodic/sampling/jfrCPUTimeThreadSampler.cpp line 279:
> 277: void JfrCPUTimeThreadSampler::disenroll() {
> 278: if (!Atomic::cmpxchg(&_disenrolled, false, true)) {
> 279: log_info(jfr)("Disenrolling CPU thread sampler");
log_trace, please.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2121414317
PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2121416556
PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2121426574
PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2121428073
More information about the hotspot-dev
mailing list