On Thu, 7 Aug 2025 14:03:40 GMT, Doug Lea <d...@openjdk.org> wrote:
>> This set of updates reduces contention-based performance loss under heavy
>> over-subscription, while also improving perfomance more generally.
>
> Doug Lea has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Avoid underutilization on resize
src/java.base/share/classes/java/util/concurrent/Exchanger.java line 380:
> 378:
> (!ForkJoinWorkerThread.hasKnownQueuedWork()))) {
> 379: for (int j = SPINS; p.match == null && j >
> 0; --j)
> 380: Thread.onSpinWait();
It might not be worth it, but I wonder if something like this would make a
positive impact:
Suggestion:
if (!(tryCancel = (deadline != 0L &&
(ns = deadline - System.nanoTime()) <= 0L) ||
Thread.currentThread().isInterrupted()))
&& ncpu > 1 &&
(i != 0 || /* check for busy VTs */
(!ForkJoinWorkerThread.hasKnownQueuedWork()))) {
for (int j = SPINS; p.match == null && j > 0; --j)
Thread.onSpinWait();
src/java.base/share/classes/java/util/concurrent/Exchanger.java line 408:
> 406: if (Thread.interrupted())
> 407: throw new InterruptedException();
> 408: if (deadline != 0L && ns <= 0L)
Is the reasoning here that `deadline` cannot be == 0L, or that it doesn't
matter anymore if it is?
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/26479#discussion_r2276356973
PR Review Comment: https://git.openjdk.org/jdk/pull/26479#discussion_r2276362959
