[crac] RFR: 8350088: [CRaC] Stop & restart JFR recording on checkpoint

[Radim Vansa]

On Fri, 14 Feb 2025 16:28:23 GMT, Radim Vansa <rvansa at openjdk.org> wrote:

> All JFR recordings are closed during checkpoint. After restore JDK starts new recordings with the same parameters as those running before checkpoint. The recordings dumped before checkpoint would be overwritten (as this is a new recording it won't append to the old one).
> If `-XX:StartFlightRecorder=...` is passed on restore a new recording is started.

The way how we start a new recording with `-XX:StartFlightRecorder=` on restore is rather convoluted, but there are dependencies in the order and we don't want to force classloading of JFR classes unless the recording is really started. If you think that the process requires more explanation in some parts of the close please put up your suggestions.

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PR Comment: https://git.openjdk.org/crac/pull/203#issuecomment-2659778453