RFR: 8352251: Implement JEP 518: JFR Cooperative Sampling [v22]

[Patricio Chilano Mateo]

On Wed, 14 May 2025 15:30:03 GMT, Markus Grönlund <mgronlun at openjdk.org> wrote:

>> Also, for the sampling in native case, we could make it more cooperative by adding a handshake operation like the one for all threads but for a list of threads. That way we can try to distribute the work instead of going one by one (this can actually be done with the current code too with some changes).
>
> There might be opportunities for generalizations. The main reason was to keep much of the existing JFR sampler mechanism. It evolved more and more towards handshakes, I agree. Maybe we can generalize it later.

Sure, we can leave it as a follow up. Note though that the handshake patch is mainly replacing the new sampler sync changes (_sample_monitor, _sample_request, SafepointMechanism changes, etc) since they pretty much mimic what we can do with handshakes already.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24296#discussion_r2091632646