diff --git a/components/configstores/configstore.go b/components/configstores/configstore.go
index 741346f3b9..aad351bff5 100644
--- a/components/configstores/configstore.go
+++ b/components/configstores/configstore.go
@@ -53,7 +53,9 @@ type Store interface {
 	//StopSubscribe stop subs
 	StopSubscribe()
 
+	// GetDefaultGroup returns default group.This method will be invoked if a request doesn't specify the group field
 	GetDefaultGroup() string
 
+	// GetDefaultLabel returns default label
 	GetDefaultLabel() string
 }
diff --git a/pkg/grpc/api.go b/pkg/grpc/api.go
index 5713dd688e..a27e943c73 100644
--- a/pkg/grpc/api.go
+++ b/pkg/grpc/api.go
@@ -270,43 +270,58 @@ func (a *api) SubscribeConfiguration(sub runtimev1pb.Runtime_SubscribeConfigurat
 	respCh := make(chan *configstores.SubscribeResp)
 	recvExitCh := make(chan struct{})
 	subscribedStore := make([]configstores.Store, 0, 1)
+	// TODO currently this goroutine model is error-prone,and it should be refactored after new version of configuration API being accepted
+	// 1. start a reader goroutine
 	go func() {
 		defer wg.Done()
 		for {
+			// 1.1. read stream
 			req, err := sub.Recv()
+			// 1.2. if an error happens,stop all the subscribers
 			if err != nil {
 				log.DefaultLogger.Errorf("occur error in subscribe, err: %+v", err)
+				// stop all the subscribers
 				for _, store := range subscribedStore {
+					// TODO this method will stop subscribers created by other connections.Should be refactored
 					store.StopSubscribe()
 				}
 				subErr = err
-				if len(subscribedStore) == 0 {
-					close(recvExitCh)
-				}
+				// stop writer goroutine
+				close(recvExitCh)
 				return
 			}
+			// 1.3. else find the component and delegate to it
 			store, ok := a.configStores[req.StoreName]
+			// 1.3.1. stop if StoreName is not supported
 			if !ok {
 				log.DefaultLogger.Errorf("configure store [%+v] don't support now", req.StoreName)
+				// stop all the subscribers
+				for _, store := range subscribedStore {
+					store.StopSubscribe()
+				}
 				subErr = errors.New(fmt.Sprintf("configure store [%+v] don't support now", req.StoreName))
+				// stop writer goroutine
 				close(recvExitCh)
 				return
 			}
+			// 1.3.2. use default settings if blank
 			if strings.ReplaceAll(req.Group, " ", "") == "" {
 				req.Group = store.GetDefaultGroup()
 			}
 			if strings.ReplaceAll(req.Label, " ", "") == "" {
 				req.Label = store.GetDefaultLabel()
 			}
+			// 1.3.3. delegate to the component
 			store.Subscribe(&configstores.SubscribeReq{AppId: req.AppId, Group: req.Group, Label: req.Label, Keys: req.Keys, Metadata: req.Metadata}, respCh)
 			subscribedStore = append(subscribedStore, store)
 		}
 	}()
-
+	// 2. start a writer goroutine
 	go func() {
 		defer wg.Done()
 		for {
 			select {
+			// read response from components
 			case resp, ok := <-respCh:
 				if !ok {
 					return
@@ -315,7 +330,9 @@ func (a *api) SubscribeConfiguration(sub runtimev1pb.Runtime_SubscribeConfigurat
 				for _, item := range resp.Items {
 					items = append(items, &runtimev1pb.ConfigurationItem{Group: item.Group, Label: item.Label, Key: item.Key, Content: item.Content, Tags: item.Tags, Metadata: item.Metadata})
 				}
+				// write to response stream
 				sub.Send(&runtimev1pb.SubscribeConfigurationResponse{StoreName: resp.StoreName, AppId: resp.StoreName, Items: items})
+			//	read exit signal
 			case <-recvExitCh:
 				return
 			}
diff --git a/pkg/grpc/api_test.go b/pkg/grpc/api_test.go
index 8bd5f3134b..6af67cf932 100644
--- a/pkg/grpc/api_test.go
+++ b/pkg/grpc/api_test.go
@@ -162,16 +162,18 @@ func TestDeleteConfiguration(t *testing.T) {
 
 func TestSubscribeConfiguration(t *testing.T) {
 	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
 	mockConfigStore := mock.NewMockStore(ctrl)
+	api := NewAPI("", nil, map[string]configstores.Store{"mock": mockConfigStore}, nil, nil, nil, nil)
+
 	//test not support store type
 	grpcServer := &MockGrpcServer{req: &runtimev1pb.SubscribeConfigurationRequest{}, err: nil}
-	api := NewAPI("", nil, map[string]configstores.Store{"mock": mockConfigStore}, nil, nil, nil, nil)
 	err := api.SubscribeConfiguration(grpcServer)
 	assert.NotNil(t, err)
 	assert.Equal(t, err.Error(), "configure store [] don't support now")
 
 	//test
-	mockConfigStore.EXPECT().StopSubscribe().Return().Times(1)
 	grpcServer2 := &MockGrpcServer{req: &runtimev1pb.SubscribeConfigurationRequest{}, err: errors.New("exit")}
 	err = api.SubscribeConfiguration(grpcServer2)
 	assert.NotNil(t, err)