store/tikv: fix goroutine leak in gcworker (pingcap#10622)

store/tikv/range_task.go

@@ -129,8 +129,6 @@ func (s *RangeTaskRunner) RunOnRange(ctx context.Context, startKey []byte, endKe
 	key := startKey
 	for {
 		select {
-		case <-ctx.Done():
-			return errors.Trace(ctx.Err())
 		case <-statLogTicker.C:
 			logutil.Logger(ctx).Info("range task in progress",
 				zap.String("name", s.name),
@@ -168,7 +166,12 @@ func (s *RangeTaskRunner) RunOnRange(ctx context.Context, startKey []byte, endKe
 		}
 
 		pushTaskStartTime := time.Now()
-		taskCh <- task
+
+		select {
+		case taskCh <- task:
+		case <-ctx.Done():
+			break
+		}
 		metrics.TiKVRangeTaskPushDuration.WithLabelValues(s.name).Observe(time.Since(pushTaskStartTime).Seconds())
 
 		if isLast {
@@ -247,8 +250,6 @@ func (w *rangeTaskWorker) run(ctx context.Context, cancel context.CancelFunc) {
 		}
 
 		completedRegions, err := w.handler(ctx, *r)
-		atomic.AddInt32(w.completedRegions, int32(completedRegions))
-
 		if err != nil {
 			logutil.Logger(ctx).Info("canceling range task because of error",
 				zap.String("name", w.name),
@@ -259,5 +260,6 @@ func (w *rangeTaskWorker) run(ctx context.Context, cancel context.CancelFunc) {
 			cancel()
 			break
 		}
+		atomic.AddInt32(w.completedRegions, int32(completedRegions))
 	}
 }