RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v17]

[Markus Grönlund]

On Mon, 26 May 2025 20:57:15 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:
> 
>   Remove assertion

src/hotspot/share/jfr/periodic/sampling/jfrSampleRequest.cpp line 174:

> 172:   assert(request._sample_pc != nullptr, "invariant");
> 173:   assert(jt != nullptr, "invariant");
> 174:   assert(jt->thread_state() == _thread_in_Java, "invariant");

What?

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PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2108902215