On Sun, 7 Sep 2025 18:28:54 GMT, Doug Lea <[email protected]> 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:
>
> revive topLevelExec, adjust occrdingly; small teaks and copy-edits
src/java.base/share/classes/java/util/concurrent/Exchanger.java line 276:
> 274: static final class Node {
> 275: long seed; // Random seed
> 276: int index; // Arena index
Just adding it here as a reminder (to myself if nothing else) that the changes
to Exchanger.java should be in a separate PR for easier handling.
src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java line 575:
> 573: * or non-emptiness; all of which usually cause more activations
> 574: * than necessary (see below). (Method signalWork is also used as
> 575: * failsafe in case of Thread failures in deregisterWorker.)
I think it is worth elaborating what this failsafe enables (i.e. how does it
failsafe these failures)
src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java line 598:
> 596: * needs unparking upon signal.
> 597: *
> 598: * When tasks are constructed as (recursive) dags, top-level
Suggestion:
* When tasks are constructed as (recursive) DAGs, top-level
src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java line 605:
> 603: * empty or contended, while also minimizing interference by
> 604: * postponing bookeeping to ends of runs. This may reduce
> 605: * fairness, which is partially counteracted by the following.
This sentence ends in a weird manner for me. Is the intention that the dot
should be a colon? Or is there missing text?
src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java line 612:
> 610: * stalls when tasks cannot be taken because other workers have
> 611: * not finished poll operations, which is detected by reading
> 612: * ahead in queue arrays. In both caes, workers restart scans in a
Suggestion:
* ahead in queue arrays. In both cases, workers restart scans in a
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/26479#discussion_r2340616981
PR Review Comment: https://git.openjdk.org/jdk/pull/26479#discussion_r2340606205
PR Review Comment: https://git.openjdk.org/jdk/pull/26479#discussion_r2340607680
PR Review Comment: https://git.openjdk.org/jdk/pull/26479#discussion_r2340612511
PR Review Comment: https://git.openjdk.org/jdk/pull/26479#discussion_r2340613633
