RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v5]

[Johannes Bechberger]

On Sun, 25 May 2025 16:16:33 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

>> Johannes Bechberger has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix compilation
>
> src/hotspot/share/jfr/periodic/sampling/jfrCPUTimeThreadSampler.cpp line 365:
> 
>> 363:   // idea: this ensures that the frames happened in native
>> 364:   // maybe we can wrap this in #ifdef ASSERT if first_index is always 0
>> 365:   s4 first_index = queue.size() - 1;
> 
> I'm afraid I don't understand this logic at all. If the intent is to share a sid over many requests, why are the individual requests passed to stacktrace.record_inner()?

I rewrote the code and store the first native request index directly in the queue. Therefore we only need to walk the queue once.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2106997891