Withdrawn: 8326012: JFR: Event for time to safepoint

[Denghui Dong]

On Fri, 16 Feb 2024 03:59:36 GMT, Denghui Dong <ddong at openjdk.org> wrote:

> There are now some JFR events related to safepoint. When time-to-safepoint (aka ttsp) is too long, these events could not be very helpful since based on them we cannot know which threads cause it and what those threads are doing.
> 
> Users can use `-XX:+SafepointTimeout -XX:SafepointTimeoutDelay=100` to see the threads that don't reach safepoint in time but without stack traces. Using `-XX:+ AbortVMOnSafepointTimeout` can capture the stack traces but it crashes the process, hence it's not sensible to enable the flag in production.
> 
> ~~This patch adds a new JFR event `EventSafepointTimeout` to record the threads that cause ttsp too long.~~
> 
> ~~This event includes two fields:~~
> 
> ~~- safepointId: the relevant safepoint id~~
> ~~- timeExceeded: the amount of time exceeding `SafepointTimeoutDelay` used by the thread to reach safepoint~~
> 
> ~~In the current version, this event records the stack of those problematic threads when they finally reach safepoint. Hence, there is a bias, but it's still helpful to deduce the root place.~~
> 
> A better implementation is to record a more accurate stack, but this will increase complexity. At the same time, the native stack may also be important for this problem, but it is not currently supported by JFR.
> 
> Any input would be greatly appreciated.
> 
> Testing: jdk/jdk/jfr

This pull request has been closed without being integrated.

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PR: https://git.openjdk.org/jdk/pull/17888