RFR: 8342818: Implement JEP 509: JFR CPU-Time Profiling [v5]

[Markus Grönlund]

On Mon, 26 May 2025 08:30:00 GMT, Johannes Bechberger <jbechberger at openjdk.org> wrote:

>> A thread in native is still stackwalked at a safe location, a safepoint code position.
>> 
>> It's guaranteed by the last java frame (ljf).
>
> Yes, but it might be an indeterminate time between entering and exiting the native thread state. So I need to walk them in between. Your sampler implementation also walks threads in native state.

That's fine. Its the term "out of safepoint" which is a concept that does not refer to anything concrete.

"Sampling" is the process of saving and enqueing a JfrSampleRequest.

"Stackwalking" or "processing of enqueued requests" is another thing. Are you referring to the second here?

"out of safepoint" does not make any sense.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25302#discussion_r2106887879