*: close ticker when function returns (#4053)

Signed-off-by: Ryan Leung <rleungx@gmail.com>

Co-authored-by: Ti Chi Robot <ti-community-prow-bot@tidb.io>

server/cluster/coordinator_test.go

@@ -887,13 +887,13 @@ func BenchmarkPatrolRegion(b *testing.B) {
 		for {
 			if oc.OperatorCount(operator.OpMerge) == mergeLimit {
 				co.cancel()
-				co.wg.Add(1)
 				return
 			}
 		}
 	}()
 	<-listen
 
+	co.wg.Add(1)
 	b.ResetTimer()
 	co.patrolRegions()
 }

server/core/region_storage.go

@@ -72,35 +72,33 @@ func NewRegionStorage(
 		regionStorageCtx:     regionStorageCtx,
 		regionStorageCancel:  regionStorageCancel,
 	}
-	s.backgroundFlush()
+	go s.backgroundFlush()
 	return s, nil
 }
 
 func (s *RegionStorage) backgroundFlush() {
-	ticker := time.NewTicker(dirtyFlushTick)
 	var (
 		isFlush bool
 		err     error
 	)
-	go func() {
-		defer ticker.Stop()
-		for {
-			select {
-			case <-ticker.C:
-				s.mu.RLock()
-				isFlush = s.flushTime.Before(time.Now())
-				s.mu.RUnlock()
-				if !isFlush {
-					continue
-				}
-				if err = s.FlushRegion(); err != nil {
-					log.Error("flush regions meet error", errs.ZapError(err))
-				}
-			case <-s.regionStorageCtx.Done():
-				return
+	ticker := time.NewTicker(dirtyFlushTick)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-ticker.C:
+			s.mu.RLock()
+			isFlush = s.flushTime.Before(time.Now())
+			s.mu.RUnlock()
+			if !isFlush {
+				continue
 			}
+			if err = s.FlushRegion(); err != nil {
+				log.Error("flush regions meet error", errs.ZapError(err))
+			}
+		case <-s.regionStorageCtx.Done():
+			return
 		}
-	}()
+	}
 }
 
 // SaveRegion saves one region to storage.

server/region_syncer/server.go

@@ -106,6 +106,7 @@ func (s *RegionSyncer) RunServer(regionNotifier <-chan *core.RegionInfo, quit ch
 	var stats []*pdpb.RegionStat
 	var leaders []*metapb.Peer
 	ticker := time.NewTicker(syncerKeepAliveInterval)
+	defer ticker.Stop()
 	for {
 		select {
 		case <-quit:

tools/pd-tso-bench/main.go

@@ -142,6 +142,7 @@ func showStats(ctx context.Context, durCh chan time.Duration) {
 	defer cancel()
 
 	ticker := time.NewTicker(*interval)
+	defer ticker.Stop()
 
 	s := newStats()
 	total := newStats()