diff --git a/Makefile b/Makefile
index caa4eada..72a53020 100644
--- a/Makefile
+++ b/Makefile
@@ -324,8 +324,8 @@ rpm-server-arm64: server-linux-arm64
 test-binary:
 	CGO_ENABLED=0 go build -ldflags="-X 'github.com/enfein/mieru/pkg/log.LogPrefix=C'" -o mieru cmd/mieru/mieru.go
 	CGO_ENABLED=0 go build -ldflags="-X 'github.com/enfein/mieru/pkg/log.LogPrefix=S'" -o mita cmd/mita/mita.go
-	CGO_ENABLED=0 go build -ldflags="-X 'github.com/enfein/mieru/pkg/log.LogPrefix=C2'" -o mieru2 cmd/mieru/mieru.go
-	CGO_ENABLED=0 go build -ldflags="-X 'github.com/enfein/mieru/pkg/log.LogPrefix=S2'" -o mita2 cmd/mita/mita.go
+	CGO_ENABLED=1 go build -race -ldflags="-X 'github.com/enfein/mieru/pkg/log.LogPrefix=C2'" -o mieru2 cmd/mieru/mieru.go
+	CGO_ENABLED=1 go build -race -ldflags="-X 'github.com/enfein/mieru/pkg/log.LogPrefix=S2'" -o mita2 cmd/mita/mita.go
 	CGO_ENABLED=0 go build test/cmd/httpserver/httpserver.go
 	CGO_ENABLED=0 go build test/cmd/sockshttpclient/sockshttpclient.go
 	CGO_ENABLED=0 go build test/cmd/socksudpclient/socksudpclient.go
diff --git a/pkg/appctl/server.go b/pkg/appctl/server.go
index de486def..fa0fc264 100644
--- a/pkg/appctl/server.go
+++ b/pkg/appctl/server.go
@@ -97,13 +97,13 @@ func (s *serverLifecycleService) Start(ctx context.Context, req *pb.Empty) (*pb.
 	if err != nil {
 		return &pb.Empty{}, fmt.Errorf("LoadServerConfig() failed: %w", err)
 	}
+	if err = ValidateFullServerConfig(config); err != nil {
+		return &pb.Empty{}, fmt.Errorf("ValidateFullServerConfig() failed: %w", err)
+	}
 	loggingLevel := config.GetLoggingLevel().String()
 	if loggingLevel != pb.LoggingLevel_DEFAULT.String() {
 		log.SetLevel(loggingLevel)
 	}
-	if err = ValidateFullServerConfig(config); err != nil {
-		return &pb.Empty{}, fmt.Errorf("ValidateFullServerConfig() failed: %w", err)
-	}
 	if socks5ServerRef.Load() != nil {
 		log.Infof("socks5 server already exist")
 		return &pb.Empty{}, nil
@@ -196,6 +196,29 @@ func (s *serverLifecycleService) Stop(ctx context.Context, req *pb.Empty) (*pb.E
 	return &pb.Empty{}, nil
 }
 
+func (s *serverLifecycleService) Reload(ctx context.Context, req *pb.Empty) (*pb.Empty, error) {
+	log.Infof("received start request from RPC caller")
+	config, err := LoadServerConfig()
+	if err != nil {
+		return &pb.Empty{}, fmt.Errorf("LoadServerConfig() failed: %w", err)
+	}
+	if err = ValidateFullServerConfig(config); err != nil {
+		return &pb.Empty{}, fmt.Errorf("ValidateFullServerConfig() failed: %w", err)
+	}
+	mux := serverMuxRef.Load()
+	// Adjust portBindings.
+	// Adjust users.
+	if mux != nil {
+		mux.SetServerUsers(UserListToMap(config.GetUsers()))
+	}
+	// Adjust loggingLevel.
+	loggingLevel := config.GetLoggingLevel().String()
+	if loggingLevel != pb.LoggingLevel_DEFAULT.String() {
+		log.SetLevel(loggingLevel)
+	}
+	return &pb.Empty{}, nil
+}
+
 func (s *serverLifecycleService) Exit(ctx context.Context, req *pb.Empty) (*pb.Empty, error) {
 	SetAppStatus(pb.AppStatus_STOPPING)
 	log.Infof("received exit request from RPC caller")
diff --git a/pkg/protocolv2/segment.go b/pkg/protocolv2/segment.go
index f7b70636..5ea7214c 100644
--- a/pkg/protocolv2/segment.go
+++ b/pkg/protocolv2/segment.go
@@ -240,7 +240,7 @@ func (t *segmentTree) DeleteMin() (*segment, bool) {
 	t.mu.Lock()
 	defer t.mu.Unlock()
 
-	if t.Len() == 0 {
+	if t.tr.Len() == 0 {
 		return nil, false
 	}
 	seg, ok := t.tr.DeleteMin()
@@ -251,7 +251,7 @@ func (t *segmentTree) DeleteMin() (*segment, bool) {
 		panic("segmentTree.DeleteMin() return nil")
 	}
 	t.notFull.Broadcast()
-	if t.Len() > 0 {
+	if t.tr.Len() > 0 {
 		t.notifyNotEmpty()
 	} else {
 		t.notifyEmpty()
@@ -266,7 +266,7 @@ func (t *segmentTree) DeleteMinIf(si segmentIterator) (*segment, bool) {
 	t.mu.Lock()
 	defer t.mu.Unlock()
 
-	if t.Len() == 0 {
+	if t.tr.Len() == 0 {
 		return nil, false
 	}
 	seg, ok := t.tr.Min()
@@ -287,7 +287,7 @@ func (t *segmentTree) DeleteMinIf(si segmentIterator) (*segment, bool) {
 		}
 		t.notFull.Broadcast()
 	}
-	if t.Len() > 0 {
+	if t.tr.Len() > 0 {
 		t.notifyNotEmpty()
 	} else {
 		t.notifyEmpty()
@@ -337,11 +337,15 @@ func (t *segmentTree) MaxSeq() (uint32, error) {
 
 // Len returns the current size of the tree.
 func (t *segmentTree) Len() int {
+	t.mu.Lock()
+	defer t.mu.Unlock()
 	return t.tr.Len()
 }
 
 // Remaining returns the remaining space of the tree before it is full.
 func (t *segmentTree) Remaining() int {
+	t.mu.Lock()
+	defer t.mu.Unlock()
 	return t.cap - t.tr.Len()
 }
 
diff --git a/pkg/protocolv2/underlay_udp.go b/pkg/protocolv2/underlay_udp.go
index 3aaa924b..30b33806 100644
--- a/pkg/protocolv2/underlay_udp.go
+++ b/pkg/protocolv2/underlay_udp.go
@@ -194,12 +194,16 @@ func (u *UDPUnderlay) RunEventLoop(ctx context.Context) error {
 			// Close idle sessions.
 			u.sessionMap.Range(func(k, v any) bool {
 				session := v.(*Session)
+				select {
+				case <-session.done:
+					log.Debugf("Found closed %v", session)
+					if err := u.RemoveSession(session); err != nil {
+						log.Debugf("%v RemoveSession() failed: %v", u, err)
+					}
+				default:
+				}
 				if time.Since(session.lastRXTime) > idleSessionTimeout {
 					log.Debugf("Found idle %v", session)
-					if err := session.Close(); err != nil && !stderror.IsEOF(err) && !stderror.IsClosed(err) {
-						log.Debugf("%v Close() failed: %v", session, err)
-					}
-					session.wg.Wait()
 					if err := u.RemoveSession(session); err != nil {
 						log.Debugf("%v RemoveSession() failed: %v", u, err)
 					}