silences: avoid deadlock #995
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olive42
reviewed
Sep 15, 2017
silence/silence_test.go
Outdated
| require.Equal(t, want.data, s.st.data, "Unexpected silence state") | ||
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| // GossipBroadcast is called in a gorountine. |
Calling gossip.GossipBroadcast() will cause a deadlock if there is a currently executing OnBroadcast* function. See prometheus#982
|
LGTM |
| s.gossip.GossipBroadcast(st) | ||
| // setSilence() is called with s.mtx locked, which can produce | ||
| // a deadlock if we call GossipBroadcast from here. | ||
| go s.gossip.GossipBroadcast(st) |
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The tests still pass when I remove the go here. The tests should fail without the inclusion of this.
stuartnelson3
suggested changes
Sep 27, 2017
silence/silence_test.go
Outdated
| require.NoError(t, s.setSilence(sil)) | ||
| require.True(t, called, "GossipBroadcast was not called") | ||
| s.mtx.Unlock() |
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While this test passes because of the go, if someone were to remove the go, this deadlocks and the timeout in the select below is never called. If you re-arrange the code like below, then we have a passing test with your code 🙌 , and if someone removes the go, it will fail instead of locking up:
diff --git a/silence/silence_test.go b/silence/silence_test.go
index 420a78c..eed4060 100644
--- a/silence/silence_test.go
+++ b/silence/silence_test.go
@@ -213,11 +213,11 @@ func TestSilencesSetSilence(t *testing.T) {
}
// setSilence() is always called with s.mtx locked()
- s.mtx.Lock()
- require.NoError(t, s.setSilence(sil))
- s.mtx.Unlock()
-
- require.Equal(t, want.data, s.st.data, "Unexpected silence state")
+ go func() {
+ s.mtx.Lock()
+ require.NoError(t, s.setSilence(sil))
+ s.mtx.Unlock()
+ }()
// GossipBroadcast is called in a goroutine.
select {
@@ -225,6 +225,8 @@ func TestSilencesSetSilence(t *testing.T) {
case <-time.After(1 * time.Second):
t.Fatal("GossipBroadcast was not called")
}
+
+ require.Equal(t, want.data, s.st.data, "Unexpected silence state")
}
func TestSilenceSet(t *testing.T) {
hh
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Jul 22, 2018
…stemd 239 (prometheus#995) Signed-off-by: xginn8 <mamcgi@gmail.com>
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Calling gossip.GossipBroadcast() will cause a deadlock if
there is a currently executing OnBroadcast* function.
See #982