fix: Fix flowgraph leak (#39656)

Consider lag targets when determining whether to remove the dispatcher
manager.

issue: https://github.com/milvus-io/milvus/issues/39642

Signed-off-by: bigsheeper <yihao.dai@zilliz.com>

pkg/mq/msgdispatcher/client.go

@@ -98,13 +98,13 @@ func (c *client) Register(ctx context.Context, streamConfig *StreamConfig) (<-ch
 	}
 	// Check if the consumer number limit has been reached.
 	limit := paramtable.Get().MQCfg.MaxDispatcherNumPerPchannel.GetAsInt()
-	if manager.Num() >= limit {
+	if manager.NumConsumer() >= limit {
 		return nil, merr.WrapErrTooManyConsumers(vchannel, fmt.Sprintf("limit=%d", limit))
 	}
 	// Begin to register
 	ch, err := manager.Add(ctx, streamConfig)
 	if err != nil {
-		if manager.Num() == 0 {
+		if manager.NumTarget() == 0 {
 			manager.Close()
 			c.managers.Remove(pchannel)
 		}
@@ -122,7 +122,7 @@ func (c *client) Deregister(vchannel string) {
 	defer c.managerMut.Unlock(pchannel)
 	if manager, ok := c.managers.Get(pchannel); ok {
 		manager.Remove(vchannel)
-		if manager.Num() == 0 {
+		if manager.NumTarget() == 0 {
 			manager.Close()
 			c.managers.Remove(pchannel)
 		}

pkg/mq/msgdispatcher/manager.go

@@ -38,7 +38,8 @@ import (
 type DispatcherManager interface {
 	Add(ctx context.Context, streamConfig *StreamConfig) (<-chan *MsgPack, error)
 	Remove(vchannel string)
-	Num() int
+	NumTarget() int
+	NumConsumer() int
 	Run()
 	Close()
 }
@@ -145,7 +146,17 @@ func (c *dispatcherManager) Remove(vchannel string) {
 	c.lagTargets.GetAndRemove(vchannel)
 }
 
-func (c *dispatcherManager) Num() int {
+func (c *dispatcherManager) NumTarget() int {
+	c.mu.RLock()
+	defer c.mu.RUnlock()
+	var res int
+	if c.mainDispatcher != nil {
+		res += c.mainDispatcher.TargetNum()
+	}
+	return res + len(c.soloDispatchers) + c.lagTargets.Len()
+}
+
+func (c *dispatcherManager) NumConsumer() int {
 	c.mu.RLock()
 	defer c.mu.RUnlock()
 	var res int

pkg/mq/msgdispatcher/manager_test.go

@@ -39,7 +39,8 @@ func TestManager(t *testing.T) {
 	t.Run("test add and remove dispatcher", func(t *testing.T) {
 		c := NewDispatcherManager("mock_pchannel_0", typeutil.ProxyRole, 1, newMockFactory())
 		assert.NotNil(t, c)
-		assert.Equal(t, 0, c.Num())
+		assert.Equal(t, 0, c.NumConsumer())
+		assert.Equal(t, 0, c.NumTarget())
 
 		var offset int
 		for i := 0; i < 100; i++ {
@@ -50,14 +51,16 @@ func TestManager(t *testing.T) {
 				t.Logf("add vchannel, %s", vchannel)
 				_, err := c.Add(context.Background(), NewStreamConfig(vchannel, nil, common.SubscriptionPositionUnknown))
 				assert.NoError(t, err)
-				assert.Equal(t, offset, c.Num())
+				assert.Equal(t, offset, c.NumConsumer())
+				assert.Equal(t, offset, c.NumTarget())
 			}
 			for j := 0; j < rand.Intn(r); j++ {
 				vchannel := fmt.Sprintf("mock-pchannel-dml_0_vchannelv%d", offset)
 				t.Logf("remove vchannel, %s", vchannel)
 				c.Remove(vchannel)
 				offset--
-				assert.Equal(t, offset, c.Num())
+				assert.Equal(t, offset, c.NumConsumer())
+				assert.Equal(t, offset, c.NumTarget())
 			}
 		}
 	})
@@ -73,7 +76,8 @@ func TestManager(t *testing.T) {
 		assert.NoError(t, err)
 		_, err = c.Add(ctx, NewStreamConfig("mock_vchannel_2", nil, common.SubscriptionPositionUnknown))
 		assert.NoError(t, err)
-		assert.Equal(t, 3, c.Num())
+		assert.Equal(t, 3, c.NumConsumer())
+		assert.Equal(t, 3, c.NumTarget())
 		c.(*dispatcherManager).mainDispatcher.curTs.Store(1000)
 		c.(*dispatcherManager).mu.RLock()
 		for _, d := range c.(*dispatcherManager).soloDispatchers {
@@ -82,7 +86,8 @@ func TestManager(t *testing.T) {
 		c.(*dispatcherManager).mu.RUnlock()
 
 		c.(*dispatcherManager).tryMerge()
-		assert.Equal(t, 1, c.Num())
+		assert.Equal(t, 1, c.NumConsumer())
+		assert.Equal(t, 3, c.NumTarget())
 
 		info := &target{
 			vchannel: "mock_vchannel_2",
@@ -90,7 +95,7 @@ func TestManager(t *testing.T) {
 			ch:       nil,
 		}
 		c.(*dispatcherManager).split(info)
-		assert.Equal(t, 2, c.Num())
+		assert.Equal(t, 2, c.NumConsumer())
 	})
 
 	t.Run("test run and close", func(t *testing.T) {
@@ -104,7 +109,8 @@ func TestManager(t *testing.T) {
 		assert.NoError(t, err)
 		_, err = c.Add(ctx, NewStreamConfig("mock_vchannel_2", nil, common.SubscriptionPositionUnknown))
 		assert.NoError(t, err)
-		assert.Equal(t, 3, c.Num())
+		assert.Equal(t, 3, c.NumConsumer())
+		assert.Equal(t, 3, c.NumTarget())
 		c.(*dispatcherManager).mainDispatcher.curTs.Store(1000)
 		c.(*dispatcherManager).mu.RLock()
 		for _, d := range c.(*dispatcherManager).soloDispatchers {
@@ -117,8 +123,9 @@ func TestManager(t *testing.T) {
 		defer paramtable.Get().Reset(checkIntervalK)
 		go c.Run()
 		assert.Eventually(t, func() bool {
-			return c.Num() == 1 // expected merged
+			return c.NumConsumer() == 1 // expected merged
 		}, 3*time.Second, 10*time.Millisecond)
+		assert.Equal(t, 3, c.NumTarget())
 
 		assert.NotPanics(t, func() {
 			c.Close()
@@ -140,7 +147,8 @@ func TestManager(t *testing.T) {
 		assert.Error(t, err)
 		_, err = c.Add(ctx, NewStreamConfig("mock_vchannel_2", nil, common.SubscriptionPositionUnknown))
 		assert.Error(t, err)
-		assert.Equal(t, 0, c.Num())
+		assert.Equal(t, 0, c.NumConsumer())
+		assert.Equal(t, 0, c.NumTarget())
 
 		assert.NotPanics(t, func() {
 			c.Close()
@@ -374,9 +382,10 @@ func (suite *SimulationSuite) TestMerge() {
 	}
 
 	suite.Eventually(func() bool {
-		suite.T().Logf("dispatcherManager.dispatcherNum = %d", suite.manager.Num())
+		suite.T().Logf("dispatcherManager.dispatcherNum = %d", suite.manager.NumConsumer())
-		return suite.manager.Num() == 1 // expected all merged, only mainDispatcher exist
+		return suite.manager.NumConsumer() == 1 // expected all merged, only mainDispatcher exist
 	}, 15*time.Second, 100*time.Millisecond)
+	assert.Equal(suite.T(), vchannelNum, suite.manager.NumTarget())
 
 	cancel()
 	wg.Wait()
@@ -409,9 +418,10 @@ func (suite *SimulationSuite) TestSplit() {
 	}
 
 	suite.Eventually(func() bool {
-		suite.T().Logf("dispatcherManager.dispatcherNum = %d, splitNum+1 = %d", suite.manager.Num(), splitNum+1)
+		suite.T().Logf("dispatcherManager.dispatcherNum = %d, splitNum+1 = %d", suite.manager.NumConsumer(), splitNum+1)
-		return suite.manager.Num() == splitNum+1 // expected 1 mainDispatcher and `splitNum` soloDispatchers
+		return suite.manager.NumConsumer() == splitNum+1 // expected 1 mainDispatcher and `splitNum` soloDispatchers
 	}, 10*time.Second, 100*time.Millisecond)
+	assert.Equal(suite.T(), vchannelNum, suite.manager.NumTarget())
 
 	cancel()
 }