RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v26]

[Johannes Bechberger]

On Sun, 1 Jun 2025 15:01:06 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

>> Johannes Bechberger has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Refactoring
>>  - Remove convoluted native trace logic
>
> src/hotspot/share/jfr/periodic/sampling/jfrThreadSampling.cpp line 362:
> 
>> 360:   drain_enqueued_requests(now, tl, jt, current);
>> 361: #ifdef LINUX
>> 362:   if (tl->has_cpu_time_jfr_requests()) {
> 
> You are having all threads traverse over this lock, even though the cpu time sampler is disabled by default. Can it be improved?

Not without allocating in the signal handler

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PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2119243238