RFR: JDK-8319662 ForkJoinPool trims worker threads too slowly [v8]

[kerr]

On Fri, 12 Jan 2024 13:41:39 GMT, kerr <duke at openjdk.org> wrote:

>> Doug Lea has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 10 additional commits since the last revision:
>> 
>>  - Merge branch 'openjdk:master' into JDK-8319662
>>  - Remove unnecessary re-interrupt
>>  - Merge branch 'openjdk:master' into JDK-8319662
>>  - Reduce oversignalling and contention; add test
>>  - Revert 2 lines in method scan
>>  - Merge branch 'openjdk:master' into JDK-8319662
>>  - Split up method awaitWork; other associated changes.
>>  - Merge branch 'openjdk:master' into JDK-8319662
>>  - tweak cascades; reinstate an @Contended; resolve JDK-8319498
>>  - Support cascading idle timeouts
>
> Cool, I just encounter this problem, when I migrate to Virtual threads and set  `jdk.virtualThreadScheduler.maxPoolSize` to 2500.
> 
> Will this change backport to j21u, thanks.

> @He-Pin I tried to backport this patch for you just now [1]. But it can't be automatically backported because JDK-8288899 [2][3] also revised the file `src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java`. Do you want to backport these two patches? Or only this one?
> 
> [1] https://github.com/openjdk/jdk/commit/cc25d8b12bbab9dde9ade7762927dcb8d27e23c5#commitcomment-136982984
> [2] https://bugs.openjdk.org/browse/JDK-8288899
> [3] https://git.openjdk.org/jdk/pull/14301

I think the related issue should be backported too.

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PR Comment: https://git.openjdk.org/jdk/pull/16725#issuecomment-1890750696