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| author | Cherry Zhang <cherryyz@google.com> | 2020-03-16 20:08:00 -0400 |
|---|---|---|
| committer | Cherry Zhang <cherryyz@google.com> | 2020-03-18 16:00:44 +0000 |
| commit | 0c0e8f224d5724e317952f77d215a752a3a7b7d9 (patch) | |
| tree | c190a79fde5ddd44ab0987067accfc3ae84b597e /src/runtime/signal_unix.go | |
| parent | 6412750f32224f6820f781d09b2092c5c358dddc (diff) | |
| download | go-0c0e8f224d5724e317952f77d215a752a3a7b7d9.tar.gz go-0c0e8f224d5724e317952f77d215a752a3a7b7d9.zip | |
runtime: don't send preemption signal if there is a signal pending
If multiple threads call preemptone to preempt the same M, it may
send many signals to the same M such that it hardly make
progress, causing live-lock problem. Only send a signal if there
isn't already one pending.
Fixes #37741.
Change-Id: Id94adb0b95acbd18b23abe637a8dcd81ab41b452
Reviewed-on: https://go-review.googlesource.com/c/go/+/223737
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Diffstat (limited to 'src/runtime/signal_unix.go')
| -rw-r--r-- | src/runtime/signal_unix.go | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/src/runtime/signal_unix.go b/src/runtime/signal_unix.go index 32b192c977..b8f27d1147 100644 --- a/src/runtime/signal_unix.go +++ b/src/runtime/signal_unix.go @@ -333,6 +333,7 @@ func doSigPreempt(gp *g, ctxt *sigctxt) { // Acknowledge the preemption. atomic.Xadd(&gp.m.preemptGen, 1) + atomic.Store(&gp.m.signalPending, 0) } const preemptMSupported = pushCallSupported @@ -359,7 +360,14 @@ func preemptM(mp *m) { // required). return } - signalM(mp, sigPreempt) + if atomic.Cas(&mp.signalPending, 0, 1) { + // If multiple threads are preempting the same M, it may send many + // signals to the same M such that it hardly make progress, causing + // live-lock problem. Apparently this could happen on darwin. See + // issue #37741. + // Only send a signal if there isn't already one pending. + signalM(mp, sigPreempt) + } } // sigFetchG fetches the value of G safely when running in a signal handler. |