RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v29]

[Markus Grönlund]

On Mon, 2 Jun 2025 13:50:49 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:
> 
>   Fix bug related to async stack walking

src/hotspot/share/jfr/periodic/sampling/jfrThreadSampling.cpp line 250:

> 248:       break;
> 249:     } else {
> 250:       biased = false;

Not correct. There is a top_frame = *current - >biased = true below.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2121482514