RFR: 8360046: Scalability issue when submitting virtual threads with almost empty tasks [v4]

[Doug Lea]

On Thu, 14 Aug 2025 11:30:01 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 11 additional commits since the last revision:
>> 
>>  - Merge branch 'openjdk:master' into JDK-8360046
>>  - Undo inadvertent acquire change
>>  - Add adapt(callable) case to test
>>  - Whitespace
>>  - Merge branch 'openjdk:master' into JDK-8360046
>>  - Avoid unnecessary use of InterruptibleTask; misc cleanup
>>  - revert runWorker; tweak external probes
>>  - reduce contention
>>  - Merge branch 'openjdk:master' into JDK-8360046
>>  - For testing
>>  - ... and 1 more: https://git.openjdk.org/jdk/compare/3be13288...c16c1282
>
> src/java.base/share/classes/java/util/concurrent/Exchanger.java line 408:
> 
>> 406:                             else if ((b & MMASK) != 0) {
>> 407:                                 misses = 0;      // try to shrink
>> 408:                                 BOUND.compareAndSet(this, b, b - 1 + SEQ);
> 
> Is the reasoning here that `deadline` cannot be == 0L, or that it doesn't matter anymore if it is?

(No longer applicable -- moved to different PR)

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PR Review Comment: https://git.openjdk.org/jdk/pull/26479#discussion_r2348829095