[crac] RFR: Ensure all notifications finish even if only daemon threads remain [v4]

[Radim Vansa]

On Fri, 5 May 2023 11:16:50 GMT, Anton Kozlov <akozlov at openjdk.org> wrote:

>> If as a result of beforeCheckpoint() no more non-daemon threads remain, it's possible that VM exits prematurely, before one of afterRestore() get a chance to create another non-daemon thread that will keep VM alive. Triggering checkpoint via jcmd (so checkpointRestore() method is executed on daemon attach-listener thread), increases probability to step in the problem.
>> 
>> The change ensures all notifications are done while there is at least one non-daemon thread. The notification methods are still called from the original thread.
>
> Anton Kozlov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Cleanup

src/java.base/share/classes/jdk/crac/Core.java line 287:

> 285:                     try {
> 286:                         keepAlive = new KeepAlive();
> 287:                     } catch (InterruptedException e) {

Upon catching InterruptedException you should set thread interrupted status.

Any reason to use RuntimeException than CheckpointException? (preferrably in a comment).

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PR Review Comment: https://git.openjdk.org/crac/pull/62#discussion_r1186258857