RFR: 8373118: Test java/lang/Thread/virtual/Starvation.java timed out [v21]

[Doug Lea]

On Thu, 8 Jan 2026 16:47:08 GMT, Viktor Klang <vklang at openjdk.org> wrote:

>> Doug Lea has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Change signalWork fencing; in-progress activation changes
>
> src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java line 1830:
> 
>> 1828:      */
>> 1829:     final void signalWork(WorkQueue q, int qbase) {
>> 1830:         int pc = U.getIntAcquire(this, PARALLELISM);
> 
> I like this, as this has the nice benefit of seeing potential changes to `parallelism` sooner.

It's now back to being fresh upon entry, but not upon retries, mainly because retires are now less frequent.

> src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java line 1855:
> 
>> 1853:                 break;
>> 1854:             if (c == (c = ctl) &&
>> 1855:                 c == (c = U.compareAndExchangeLong(this, CTL, c, nc))) {
> 
> Are there any measurable differences between the above and `c == (c = ctl) && U.compareAndSetLong(this, CTL, c, nc)` or `c == U.compareAndExchangeLong(this, CTL, c, nc)`? 🤔

It depends on whether there is much contention and/or much filtering. I redid some of it to take a middle ground on this, and results seems almost always better. (Which made me realized that I should reconsider a few other constructions elsewhere.)

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PR Review Comment: https://git.openjdk.org/jdk/pull/28797#discussion_r2679952355
PR Review Comment: https://git.openjdk.org/jdk/pull/28797#discussion_r2679948199