Add mutex prevent data race

Signed-off-by: Congqi Xia <[email protected]>

Author: congqixia

internal/querycoordv2/server.go

@@ -80,6 +80,7 @@ type Server struct {
 	address             string
 	session             sessionutil.SessionInterface
 	sessionWatcher      sessionutil.SessionWatcher
+	sessionWatcherMu    sync.Mutex
 	kv                  kv.MetaKv
 	idAllocator         func() (int64, error)
 	metricsCacheManager *metricsinfo.MetricsCacheManager
@@ -594,9 +595,11 @@ func (s *Server) Stop() error {
 		s.cluster.Stop()
 	}
 
+	s.sessionWatcherMu.Lock()
 	if s.sessionWatcher != nil {
 		s.sessionWatcher.Stop()
 	}
+	s.sessionWatcherMu.Unlock()
 
 	s.cancel()
 	s.wg.Wait()
@@ -644,7 +647,9 @@ func (s *Server) watchNodes(revision int64) {
 	log := log.Ctx(s.ctx)
 	defer s.wg.Done()
 
+	s.sessionWatcherMu.Lock()
 	s.sessionWatcher = s.session.WatchServices(typeutil.QueryNodeRole, revision+1, s.rewatchNodes)
+	s.sessionWatcherMu.Unlock()
 	for {
 		select {
 		case <-s.ctx.Done():