Remove race condition from TestRetentionCutoff

storage/local/storage.go

@@ -132,6 +132,7 @@ type memorySeriesStorage struct {
 	options *MemorySeriesStorageOptions
 
 	loopStopping, loopStopped  chan struct{}
+	logThrottlingStopped       chan struct{}
 	maxMemoryChunks            int
 	dropAfter                  time.Duration
 	checkpointInterval         time.Duration
@@ -181,6 +182,7 @@ func NewMemorySeriesStorage(o *MemorySeriesStorageOptions) Storage {
 
 		loopStopping:               make(chan struct{}),
 		loopStopped:                make(chan struct{}),
+		logThrottlingStopped:       make(chan struct{}),
 		throttled:                  make(chan struct{}, 1),
 		maxMemoryChunks:            o.MemoryChunks,
 		dropAfter:                  o.PersistenceRetentionPeriod,
@@ -640,6 +642,9 @@ func (s *memorySeriesStorage) logThrottling() {
 	timer := time.NewTimer(time.Minute)
 	timer.Stop()
 
+	// Signal exit of the goroutine. Currently only needed by test code.
+	defer close(s.logThrottlingStopped)
+
 	for {
 		select {
 		case <-s.throttled:

storage/local/storage_test.go

@@ -379,6 +379,7 @@ func TestRetentionCutoff(t *testing.T) {
 	// Stop maintenance loop to prevent actual purging.
 	close(s.loopStopping)
 	<-s.loopStopped
+	<-s.logThrottlingStopped
 	// Recreate channel to avoid panic when we really shut down.
 	s.loopStopping = make(chan struct{})