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| author | Ben Gamari <ben@smart-cactus.org> | 2019-09-27 15:49:19 +0000 |
|---|---|---|
| committer | Moritz Angermann <moritz.angermann@gmail.com> | 2020-09-18 07:33:41 +0000 |
| commit | c89d0ef2822a9863c49f3006f80cca041a71d592 (patch) | |
| tree | 8e2ef637e21657dc4d850ca85e2b270320e3aa15 | |
| parent | 304d4078ca53aebb689a6db7d51a6123a76e99b7 (diff) | |
| download | haskell-c89d0ef2822a9863c49f3006f80cca041a71d592.tar.gz | |
rts: Use relaxed atomics on n_returning_tasks
This mitigates the warning of a benign race on n_returning_tasks in
shouldYieldCapability.
See #17261.
| -rw-r--r-- | rts/Schedule.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/rts/Schedule.c b/rts/Schedule.c index 15409b044d..d987aa5589 100644 --- a/rts/Schedule.c +++ b/rts/Schedule.c @@ -634,6 +634,9 @@ shouldYieldCapability (Capability *cap, Task *task, bool didGcLast) // Capability keeps forcing a GC and the other Capabilities make no // progress at all. + // We would usually need to hold cap->lock to look at n_returning_tasks but + // we don't here since this is just an approximate predicate (right?). + TSAN_ANNOTATE_BENIGN_RACE(&cap->n_returning_tasks, "shouldYieldCapability"); return ((pending_sync && !didGcLast) || cap->n_returning_tasks != 0 || (!emptyRunQueue(cap) && (task->incall->tso == NULL @@ -721,7 +724,7 @@ schedulePushWork(Capability *cap USED_IF_THREADS, cap0 = capabilities[i]; if (cap != cap0 && !cap0->disabled && tryGrabCapability(cap0,task)) { if (!emptyRunQueue(cap0) - || cap0->n_returning_tasks != 0 + || RELAXED_LOAD(&cap0->n_returning_tasks) != 0 || !emptyInbox(cap0)) { // it already has some work, we just grabbed it at // the wrong moment. Or maybe it's deadlocked! |