RFR: 8326012: JFR: Event for time to safepoint [v9]

[Denghui Dong]

On Tue, 27 Feb 2024 09:53:26 GMT, Erik Gahlin <egahlin at openjdk.org> wrote:

> Should thread-local handshake be included in this event, or is it better done separately, or not at all?

In my opinion, if we need to record information for thread-local handshake, we'd better do it separately.

We may need more than one event or different fields than the event that this feature focuses on. Some information that I think we need to record:
- requester thread
- target thread(s)
- the time when the target thread starts processing
- handshake reason
- isAsync
...

As for whether we need to add JFR events for thread-local handshake, I want to first see if there are any problems in real workloads due to slow thread-local handshake.

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PR Comment: https://git.openjdk.org/jdk/pull/17888#issuecomment-1966306092