RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v24]

[Daishi Tabata]

On Thu, 29 May 2025 21:56:21 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 tiny issue

src/hotspot/share/jfr/metadata/metadata.xml line 975:

> 973:   </Event>
> 974: 
> 975:   <Event name="CPUTimeSampleLoss" category="Java Virtual Machine, Profiling" label="CPU Time Method Profiling Lost Samples" description="Records that the CPU time sampler lost samples"

I'm not a reviewer, but I just wanted to comment something I noticed.
The JEP document says CPUTimeSampleLos'**t**', but the implementation says CPUTimeSampleLos'**s**'. Which one is correct?
A sentence from the JEP document:

Another new event, `jdk.CPUTimeSampleLost`, is emitted when samples are lost ...

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PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2115464262