RFR: 8358666: [REDO] Implement JEP 509: JFR CPU-Time Profiling

[Markus Grönlund]

On Thu, 5 Jun 2025 06:10:09 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

I see that this PR includes my fixes for the issues I found during this night of debugging, as detailed in the backout issue: https://bugs.openjdk.org/browse/JDK-8358628

I am approving for that reason, else all that work would have been in vain.

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Marked as reviewed by mgronlun (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/25654#pullrequestreview-2899291411