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

[Johannes Bechberger]

On Sun, 1 Jun 2025 15:18:52 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/jfrCPUTimeThreadSampler.cpp line 574:
> 
>> 572: 
>> 573:   if (queue.enqueue(request)) {
>> 574:     tl->set_has_cpu_time_jfr_requests(true);
> 
> This should only need to be set when enqueuing the first entry.

You're right

> src/hotspot/share/jfr/periodic/sampling/jfrCPUTimeThreadSampler.cpp line 581:
> 
>> 579: 
>> 580:   if (jt->thread_state() == _thread_in_native &&
>> 581:       queue.size() > queue.capacity() * 2 / 3) {
> 
> Is this logic still valid? You are only asking for a async processing depending on the load factor of the queue?

Yes, so I only start the thread walking if necessary

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2119248709
PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2119250511