RFR: 8322732: ForkJoinPool may underutilize cores in async mode [v7]

[Doug Lea]

On Wed, 29 May 2024 14:09:51 GMT, Viktor Klang <vklang 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 41 additional commits since the last revision:
>> 
>>  - Merge branch 'openjdk:master' into JDK-8322732
>>  - Add test for utilization with interdependent tasks
>>  - Un-misplace onSpinWait call
>>  - Adjust control flow
>>  - Reduce memory stalls
>>  - Merge branch 'openjdk:master' into JDK-8322732
>>  - More performance tradoffs
>>  - Address review comments
>>  - Merge branch 'openjdk:master' into JDK-8322732
>>  - Repack some fields; adjust control flow
>>  - ... and 31 more: https://git.openjdk.org/jdk/compare/ae4752d2...cf5fe55c
>
> src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java line 1969:
> 
>> 1967:                 else if ((e & SHUTDOWN) == 0)
>> 1968:                     return 0;
>> 1969:                 else if (compareAndSetCtl(c, c) && casRunState(e, e | STOP))
> 
> is the `compareAndSetCtl(c, c)` needed for the read+write fence if ctl == c?

yes.

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PR Review Comment: https://git.openjdk.org/jdk/pull/19131#discussion_r1619209374