RFR: 8352251: Implement JEP 518: JFR Cooperative Sampling [v23]

[Markus Grönlund]

On Fri, 16 May 2025 00:02:49 GMT, Patricio Chilano Mateo <pchilanomate at openjdk.org> wrote:

>> Thanks. So if we create the request as mentioned before I’m not sure that check will do it. I see it’s checking for enterSpecial instead of its caller. Also I see we only get there in the interpreted case, but the caller of enterSpecial could be compiled. I was thinking of an early check where if we are in a vthread and the sample request is not within the continuation just do a bias sampling.
>
>> Where do you suggest to place it best?
>>
> Should be in `FreezeBase::unwind_frames()`. That's where we change the anchor to the ContinuationEntry.

> Thanks. So if we create the request as mentioned before I’m not sure that check will do it. I see it’s checking for enterSpecial instead of its caller. Also I see we only get there in the interpreted case, but the caller of enterSpecial could be compiled. I was thinking of an early check where if we are in a vthread and the sample request is not within the continuation just do a bias sampling.

Can you provide me with a technical snippet describing whtat you intend here? Thanks.

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PR Review Comment: https://git.openjdk.org/jdk/pull/24296#discussion_r2092619809