RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v35]

[Markus Grönlund]

On Tue, 3 Jun 2025 12:12:53 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 two additional commits since the last revision:
> 
>  - Fix include order
>  - Tiny refactoring

src/hotspot/share/jfr/support/jfrThreadLocal.hpp line 371:

> 369:   timer_t* cpu_timer() const;
> 370: 
> 371:   // The CPU time JFR lock has four different states:

Only three different states now.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2123651646