[crac] RFR: 8350088: [CRaC] Stop & restart JFR recording on checkpoint [v6]

[Radim Vansa]

On Tue, 18 Feb 2025 13:16:11 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 are moved to a different path (`xxx.jfr` -> `xxx.<N>.jfr`, `xxx` -> `xxx.<N>` with `<N>` between 0 and 20 by default). 
>> If `-XX:StartFlightRecorder=...` is passed on restore a new recording is started.
>
> Radim Vansa has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Address review comments

@TimPushkin Thanks for the review. Note that I have added one more commit, to back up recordings rather than overwrite it. I found that this is quite practical when we want to exercise checkpoint & restore Java part several times to ensure that the `afterRestore` code is warm.

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PR Comment: https://git.openjdk.org/crac/pull/203#issuecomment-2665690877