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

[Viktor Klang]

On Fri, 12 Dec 2025 16:44:21 GMT, Doug Lea <dl at openjdk.org> wrote:

> Changes signal filtering to avoid possible starvation

src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java line 1435:

> 1433:                                 int fifo, int qbase) {
> 1434:             int stolen = 1;
> 1435:             if (task != null && q != null) {

Suggestion:

            if (task != null && q != null) { // Never null, hoist checks

src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java line 1900:

> 1898:      * giving up q is nonull and signalled slot already taken.
> 1899:      */
> 1900:     final void signalWork(WorkQueue q, int qbase) {

This is a nice improvement which also removes the risk of the underlying array for some reason (growth) getting swapped out midway.

src/java.base/share/classes/java/util/concurrent/ForkJoinPool.java line 1922:

> 1920:             else
> 1921:                 nc = (v.stackPred & LMASK) | (c & TC_MASK) | ac;
> 1922:             if (q != null && q.base - qbase > 0)

Cheaper and more robust check, I like it

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PR Review Comment: https://git.openjdk.org/jdk/pull/28797#discussion_r2615796425
PR Review Comment: https://git.openjdk.org/jdk/pull/28797#discussion_r2615797362
PR Review Comment: https://git.openjdk.org/jdk/pull/28797#discussion_r2615797950