RFR: 8342818: Implement CPU Time Profiling for JFR

[Johannes Bechberger]

On Tue, 29 Oct 2024 11:10:33 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

>> Hmm. That's not good. We could eliminate the spinlock, but that will require a thread assigning its id early in thread_state_new to prevent our old sampler from hitting it (and also the new one from skipping new threads). However, this is complex because it involves reading the tid from a Java oop, so we need to investigate if that is a valid thing to do, in those states. 
>> 
>> I have to think some more about this. Too bad you need to do this complexity.
>
> I have created this to help reduce the amount of crash protection you need to use: https://github.com/openjdk/jdk/pull/21756

I'm happy to use this in the PR once it is merged.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20752#discussion_r1820730402