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Merge pull request #6628 from gyuho/fix-waitgroup
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etcdserver: make WaitGroup.Add sync with Wait
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gyuho authored Oct 12, 2016
2 parents 546873f + 0c61d88 commit 614adb0
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Showing 2 changed files with 15 additions and 1 deletion.
14 changes: 14 additions & 0 deletions etcdserver/server.go
Original file line number Diff line number Diff line change
Expand Up @@ -235,6 +235,8 @@ type EtcdServer struct {

msgSnapC chan raftpb.Message

// wgMu blocks concurrent waitgroup mutation while server stopping
wgMu sync.RWMutex
// wg is used to wait for the go routines that depends on the server state
// to exit when stopping the server.
wg sync.WaitGroup
Expand Down Expand Up @@ -644,7 +646,9 @@ func (s *EtcdServer) run() {
}

defer func() {
s.wgMu.Lock() // block concurrent waitgroup adds in goAttach while stopping
close(s.stopping)
s.wgMu.Unlock()

sched.Stop()

Expand Down Expand Up @@ -1609,6 +1613,16 @@ func (s *EtcdServer) setCommittedIndex(v uint64) {
// goAttach creates a goroutine on a given function and tracks it using
// the etcdserver waitgroup.
func (s *EtcdServer) goAttach(f func()) {
s.wgMu.RLock() // this blocks with ongoing close(s.stopping)
defer s.wgMu.RUnlock()
select {
case <-s.stopping:
plog.Warning("server has stopped (skipping goAttach)")
return
default:
}

// now safe to add since waitgroup wait has not started yet
s.wg.Add(1)
go func() {
defer s.wg.Done()
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2 changes: 1 addition & 1 deletion etcdserver/server_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -939,8 +939,8 @@ func TestTriggerSnap(t *testing.T) {
srv.Do(context.Background(), pb.Request{Method: "PUT"})
}

srv.Stop()
<-donec
srv.Stop()
}

// TestConcurrentApplyAndSnapshotV3 will send out snapshots concurrently with
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