enhance: Speed up CDC scheduling (#44564)

Make CDC watch etcd replicate pchannel meta instead of listing them
periodically.

issue: https://github.com/milvus-io/milvus/issues/44123

---------

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

internal/cdc/controller/controller.go

@@ -19,6 +19,6 @@ package controller
 // Controller controls and schedules the CDC process.
 // It will periodically update the replications by the replicate configuration.
 type Controller interface {
-	Start()
+	Start() error
 	Stop()
 }

internal/cdc/controller/controllerimpl/controller_impl.go

@@ -18,70 +18,135 @@ package controllerimpl
 
 import (
 	"context"
+	"path"
+	"strings"
 	"sync"
-	"time"
 
+	"go.etcd.io/etcd/api/v3/mvccpb"
+	clientv3 "go.etcd.io/etcd/client/v3"
 	"go.uber.org/zap"
 
 	"github.com/milvus-io/milvus/internal/cdc/resource"
+	"github.com/milvus-io/milvus/internal/metastore/kv/streamingcoord"
 	"github.com/milvus-io/milvus/pkg/v2/log"
+	"github.com/milvus-io/milvus/pkg/v2/proto/streamingpb"
+	"github.com/milvus-io/milvus/pkg/v2/util/paramtable"
 )
 
-const checkInterval = 10 * time.Second
-
 type controller struct {
-	ctx      context.Context
-	wg       sync.WaitGroup
-	stopOnce sync.Once
-	stopChan chan struct{}
+	ctx    context.Context
+	cancel context.CancelFunc
+	wg     sync.WaitGroup
+
+	prefix string
 }
 
 func NewController() *controller {
+	ctx, cancel := context.WithCancel(context.Background())
 	return &controller{
-		ctx:      context.Background(),
-		stopChan: make(chan struct{}),
+		ctx:    ctx,
+		cancel: cancel,
+		prefix: path.Join(
+			paramtable.Get().EtcdCfg.MetaRootPath.GetValue(),
+			streamingcoord.ReplicatePChannelMetaPrefix,
+		),
 	}
 }
 
-func (c *controller) Start() {
-	log.Ctx(c.ctx).Info("CDC controller started")
+func (c *controller) Start() error {
+	c.startWatchLoop()
+	return nil
+}
+
+func (c *controller) recoverReplicatePChannelMeta(replicatePChannels []*streamingpb.ReplicatePChannelMeta) {
+	currentClusterID := paramtable.Get().CommonCfg.ClusterPrefix.GetValue()
+	for _, replicate := range replicatePChannels {
+		if !strings.Contains(replicate.GetSourceChannelName(), currentClusterID) {
+			// current cluster is not source cluster, skip create replicator
+			continue
+		}
+		log.Info("recover replicate pchannel meta",
+			zap.String("sourceChannel", replicate.GetSourceChannelName()),
+			zap.String("targetChannel", replicate.GetTargetChannelName()),
+		)
+		// Replicate manager ensures the idempotency of the creation.
+		resource.Resource().ReplicateManagerClient().CreateReplicator(replicate)
+	}
+	resource.Resource().ReplicateManagerClient().RemoveOutdatedReplicators(replicatePChannels)
+}
+
+func (c *controller) watchEvents(revision int64) clientv3.WatchChan {
+	eventCh := resource.Resource().ETCD().Watch(
+		c.ctx,
+		c.prefix,
+		clientv3.WithPrefix(),
+		clientv3.WithRev(revision),
+	)
+	log.Ctx(c.ctx).Info("succeed to watch replicate pchannel meta events",
+		zap.Int64("revision", revision), zap.String("prefix", c.prefix))
+	return eventCh
+}
+
+func (c *controller) startWatchLoop() {
 	c.wg.Add(1)
 	go func() {
 		defer c.wg.Done()
-		timer := time.NewTicker(checkInterval)
-		defer timer.Stop()
 		for {
-			select {
-			case <-c.stopChan:
-				return
-			case <-timer.C:
-				c.run()
+			channels, revision, err := ListReplicatePChannels(c.ctx, resource.Resource().ETCD(), c.prefix)
+			if err != nil && c.ctx.Err() == nil {
+				log.Ctx(c.ctx).Warn("failed to list replicate pchannels", zap.Error(err))
+				continue
+			}
+			c.recoverReplicatePChannelMeta(channels)
+			eventCh := c.watchEvents(revision)
+			err = c.watchLoop(eventCh)
+			if err == nil {
+				break
 			}
 		}
 	}()
 }
 
+func (c *controller) watchLoop(eventCh clientv3.WatchChan) error {
+	for {
+		select {
+		case <-c.ctx.Done():
+			return nil
+		case event, ok := <-eventCh:
+			if !ok {
+				panic("etcd event channel closed")
+			}
+			if err := event.Err(); err != nil {
+				log.Warn("etcd event error", zap.Error(err))
+				return err
+			}
+			for _, e := range event.Events {
+				replicate := MustParseReplicateChannelFromEvent(e)
+				log.Info("handle replicate pchannel event",
+					zap.String("sourceChannel", replicate.GetSourceChannelName()),
+					zap.String("targetChannel", replicate.GetTargetChannelName()),
+					zap.String("eventType", e.Type.String()),
+				)
+				switch e.Type {
+				case mvccpb.PUT:
+					currentClusterID := paramtable.Get().CommonCfg.ClusterPrefix.GetValue()
+					if !strings.Contains(replicate.GetSourceChannelName(), currentClusterID) {
+						// current cluster is not source cluster, skip create replicator
+						continue
+					}
+					resource.Resource().ReplicateManagerClient().CreateReplicator(replicate)
+				case mvccpb.DELETE:
+					resource.Resource().ReplicateManagerClient().RemoveReplicator(replicate)
+				}
+			}
+		}
+	}
+}
+
 func (c *controller) Stop() {
-	c.stopOnce.Do(func() {
-		log.Ctx(c.ctx).Info("CDC controller stopping...")
-		close(c.stopChan)
-		c.wg.Wait()
-		resource.Resource().ReplicateManagerClient().Close()
-		log.Ctx(c.ctx).Info("CDC controller stopped")
-	})
-}
-
-func (c *controller) run() {
-	targetReplicatePChannels, err := resource.Resource().ReplicationCatalog().ListReplicatePChannels(c.ctx)
-	if err != nil {
-		log.Ctx(c.ctx).Error("failed to get replicate pchannels", zap.Error(err))
-		return
-	}
-	// create replicators for all replicate pchannels
-	for _, replicatePChannel := range targetReplicatePChannels {
-		resource.Resource().ReplicateManagerClient().CreateReplicator(replicatePChannel)
-	}
-
-	// remove out of target replicators
-	resource.Resource().ReplicateManagerClient().RemoveOutOfTargetReplicators(targetReplicatePChannels)
+	log.Ctx(c.ctx).Info("stop CDC controller...")
+	c.cancel()
+	c.wg.Wait()
+	resource.Resource().ReplicateManagerClient().Close()
+	log.Ctx(c.ctx).Info("CDC controller stopped")
 }

internal/cdc/controller/controllerimpl/controller_impl_test.go

@@ -19,69 +19,71 @@ package controllerimpl
 import (
 	"testing"
 
-	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
+	"go.etcd.io/etcd/api/v3/mvccpb"
+	clientv3 "go.etcd.io/etcd/client/v3"
+	"google.golang.org/protobuf/proto"
 
 	"github.com/milvus-io/milvus/internal/cdc/replication"
 	"github.com/milvus-io/milvus/internal/cdc/resource"
-	"github.com/milvus-io/milvus/internal/mocks/mock_metastore"
 	"github.com/milvus-io/milvus/pkg/v2/proto/streamingpb"
 )
 
-func TestController_StartAndStop(t *testing.T) {
-	mockReplicateManagerClient := replication.NewMockReplicateManagerClient(t)
-	mockReplicateManagerClient.EXPECT().Close().Return()
-	resource.InitForTest(t,
-		resource.OptReplicateManagerClient(mockReplicateManagerClient),
-	)
-
-	ctrl := NewController()
-	assert.NotPanics(t, func() {
-		ctrl.Start()
-	})
-	assert.NotPanics(t, func() {
-		ctrl.Stop()
-	})
-}
-
-func TestController_Run(t *testing.T) {
+func TestController_StartAndStop_WithEvents(t *testing.T) {
 	mockReplicateManagerClient := replication.NewMockReplicateManagerClient(t)
 	mockReplicateManagerClient.EXPECT().Close().Return()
 
-	replicatePChannels := []*streamingpb.ReplicatePChannelMeta{
-		{
-			SourceChannelName: "test-source-channel-1",
-			TargetChannelName: "test-target-channel-1",
+	// Create test data
+	replicateMeta := &streamingpb.ReplicatePChannelMeta{
+		SourceChannelName: "by-dev-test-source-channel",
+		TargetChannelName: "by-dev-test-target-channel",
+	}
+	metaBytes, _ := proto.Marshal(replicateMeta)
+
+	// Create mock events
+	putEvent := &clientv3.Event{
+		Type: mvccpb.PUT,
+		Kv: &mvccpb.KeyValue{
+			Value: metaBytes,
 		},
 	}
-	mockReplicationCatalog := mock_metastore.NewMockReplicationCatalog(t)
-	mockReplicationCatalog.EXPECT().ListReplicatePChannels(mock.Anything).Return(replicatePChannels, nil)
-	mockReplicateManagerClient.EXPECT().CreateReplicator(replicatePChannels[0]).Return()
-	mockReplicateManagerClient.EXPECT().RemoveOutOfTargetReplicators(replicatePChannels).Return()
+
+	deleteEvent := &clientv3.Event{
+		Type: mvccpb.DELETE,
+		Kv: &mvccpb.KeyValue{
+			Value: metaBytes,
+		},
+	}
+
+	eventCh := make(chan clientv3.WatchResponse, 2)
+	// Send events
+	go func() {
+		eventCh <- clientv3.WatchResponse{
+			Events: []*clientv3.Event{putEvent},
+		}
+		eventCh <- clientv3.WatchResponse{
+			Events: []*clientv3.Event{deleteEvent},
+		}
+	}()
+
+	notifyCh := make(chan struct{}, 2)
+	mockReplicateManagerClient.EXPECT().CreateReplicator(mock.Anything).RunAndReturn(func(replicate *streamingpb.ReplicatePChannelMeta) {
+		notifyCh <- struct{}{}
+	})
+	mockReplicateManagerClient.EXPECT().RemoveReplicator(mock.Anything).RunAndReturn(func(replicate *streamingpb.ReplicatePChannelMeta) {
+		notifyCh <- struct{}{}
+	})
+
 	resource.InitForTest(t,
 		resource.OptReplicateManagerClient(mockReplicateManagerClient),
-		resource.OptReplicationCatalog(mockReplicationCatalog),
 	)
 
 	ctrl := NewController()
-	ctrl.Start()
-	defer ctrl.Stop()
-	ctrl.run()
-}
-
-func TestController_RunError(t *testing.T) {
-	mockReplicateManagerClient := replication.NewMockReplicateManagerClient(t)
-	mockReplicateManagerClient.EXPECT().Close().Return()
-
-	mockReplicationCatalog := mock_metastore.NewMockReplicationCatalog(t)
-	mockReplicationCatalog.EXPECT().ListReplicatePChannels(mock.Anything).Return(nil, assert.AnError)
-	resource.InitForTest(t,
-		resource.OptReplicateManagerClient(mockReplicateManagerClient),
-		resource.OptReplicationCatalog(mockReplicationCatalog),
-	)
-
-	ctrl := NewController()
-	ctrl.Start()
-	defer ctrl.Stop()
-	ctrl.run()
+	go ctrl.watchLoop(eventCh)
+
+	// Wait for events to be processed
+	<-notifyCh
+	<-notifyCh
+
+	ctrl.Stop()
 }

internal/cdc/controller/controllerimpl/replicate_meta_util.go

@@ -0,0 +1,56 @@
+package controllerimpl
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/cockroachdb/errors"
+	clientv3 "go.etcd.io/etcd/client/v3"
+	"google.golang.org/protobuf/proto"
+
+	"github.com/milvus-io/milvus/pkg/v2/proto/streamingpb"
+)
+
+func ListReplicatePChannels(ctx context.Context, etcdCli *clientv3.Client, prefix string) ([]*streamingpb.ReplicatePChannelMeta, int64, error) {
+	resp, err := get(ctx, etcdCli, prefix)
+	if err != nil {
+		return nil, 0, err
+	}
+	keys := make([]string, 0, resp.Count)
+	values := make([]string, 0, resp.Count)
+	for _, kv := range resp.Kvs {
+		keys = append(keys, string(kv.Key))
+		values = append(values, string(kv.Value))
+	}
+	channels := make([]*streamingpb.ReplicatePChannelMeta, 0, len(values))
+	for k, value := range values {
+		info := &streamingpb.ReplicatePChannelMeta{}
+		err = proto.Unmarshal([]byte(value), info)
+		if err != nil {
+			return nil, 0, errors.Wrapf(err, "unmarshal replicate pchannel meta %s failed", keys[k])
+		}
+		channels = append(channels, info)
+	}
+	return channels, resp.Header.Revision, nil
+}
+
+func MustParseReplicateChannelFromEvent(e *clientv3.Event) *streamingpb.ReplicatePChannelMeta {
+	meta := &streamingpb.ReplicatePChannelMeta{}
+	err := proto.Unmarshal(e.Kv.Value, meta)
+	if err != nil {
+		panic(fmt.Sprintf("failed to unmarshal replicate pchannel meta: %v", err))
+	}
+	return meta
+}
+
+func get(ctx context.Context, etcdCli *clientv3.Client, prefix string) (*clientv3.GetResponse, error) {
+	ctx1, cancel := context.WithTimeout(ctx, 30*time.Second)
+	defer cancel()
+
+	opts := []clientv3.OpOption{
+		clientv3.WithPrefix(),
+		clientv3.WithSort(clientv3.SortByKey, clientv3.SortAscend),
+	}
+	return etcdCli.Get(ctx1, prefix, opts...)
+}

internal/cdc/controller/mock_controller.go

@@ -18,8 +18,21 @@ func (_m *MockController) EXPECT() *MockController_Expecter {
 }
 
 // Start provides a mock function with no fields
-func (_m *MockController) Start() {
-	_m.Called()
+func (_m *MockController) Start() error {
+	ret := _m.Called()
+
+	if len(ret) == 0 {
+		panic("no return value specified for Start")
+	}
+
+	var r0 error
+	if rf, ok := ret.Get(0).(func() error); ok {
+		r0 = rf()
+	} else {
+		r0 = ret.Error(0)
+	}
+
+	return r0
 }
 
 // MockController_Start_Call is a *mock.Call that shadows Run/Return methods with type explicit version for method 'Start'
@@ -39,13 +52,13 @@ func (_c *MockController_Start_Call) Run(run func()) *MockController_Start_Call
 	return _c
 }
 
-func (_c *MockController_Start_Call) Return() *MockController_Start_Call {
-	_c.Call.Return()
+func (_c *MockController_Start_Call) Return(_a0 error) *MockController_Start_Call {
+	_c.Call.Return(_a0)
 	return _c
 }
 
-func (_c *MockController_Start_Call) RunAndReturn(run func()) *MockController_Start_Call {
-	_c.Run(run)
+func (_c *MockController_Start_Call) RunAndReturn(run func() error) *MockController_Start_Call {
+	_c.Call.Return(run)
 	return _c
 }
 

internal/cdc/replication/mock_replicate_manager_client.go

@@ -85,35 +85,68 @@ func (_c *MockReplicateManagerClient_CreateReplicator_Call) RunAndReturn(run fun
 	return _c
 }
 
-// RemoveOutOfTargetReplicators provides a mock function with given fields: targetReplicatePChannels
-func (_m *MockReplicateManagerClient) RemoveOutOfTargetReplicators(targetReplicatePChannels []*streamingpb.ReplicatePChannelMeta) {
-	_m.Called(targetReplicatePChannels)
+// RemoveOutdatedReplicators provides a mock function with given fields: aliveReplicates
+func (_m *MockReplicateManagerClient) RemoveOutdatedReplicators(aliveReplicates []*streamingpb.ReplicatePChannelMeta) {
+	_m.Called(aliveReplicates)
 }
 
-// MockReplicateManagerClient_RemoveOutOfTargetReplicators_Call is a *mock.Call that shadows Run/Return methods with type explicit version for method 'RemoveOutOfTargetReplicators'
-type MockReplicateManagerClient_RemoveOutOfTargetReplicators_Call struct {
+// MockReplicateManagerClient_RemoveOutdatedReplicators_Call is a *mock.Call that shadows Run/Return methods with type explicit version for method 'RemoveOutdatedReplicators'
+type MockReplicateManagerClient_RemoveOutdatedReplicators_Call struct {
 	*mock.Call
 }
 
-// RemoveOutOfTargetReplicators is a helper method to define mock.On call
-//   - targetReplicatePChannels []*streamingpb.ReplicatePChannelMeta
-func (_e *MockReplicateManagerClient_Expecter) RemoveOutOfTargetReplicators(targetReplicatePChannels interface{}) *MockReplicateManagerClient_RemoveOutOfTargetReplicators_Call {
-	return &MockReplicateManagerClient_RemoveOutOfTargetReplicators_Call{Call: _e.mock.On("RemoveOutOfTargetReplicators", targetReplicatePChannels)}
+// RemoveOutdatedReplicators is a helper method to define mock.On call
+//   - aliveReplicates []*streamingpb.ReplicatePChannelMeta
+func (_e *MockReplicateManagerClient_Expecter) RemoveOutdatedReplicators(aliveReplicates interface{}) *MockReplicateManagerClient_RemoveOutdatedReplicators_Call {
+	return &MockReplicateManagerClient_RemoveOutdatedReplicators_Call{Call: _e.mock.On("RemoveOutdatedReplicators", aliveReplicates)}
 }
 
-func (_c *MockReplicateManagerClient_RemoveOutOfTargetReplicators_Call) Run(run func(targetReplicatePChannels []*streamingpb.ReplicatePChannelMeta)) *MockReplicateManagerClient_RemoveOutOfTargetReplicators_Call {
+func (_c *MockReplicateManagerClient_RemoveOutdatedReplicators_Call) Run(run func(aliveReplicates []*streamingpb.ReplicatePChannelMeta)) *MockReplicateManagerClient_RemoveOutdatedReplicators_Call {
 	_c.Call.Run(func(args mock.Arguments) {
 		run(args[0].([]*streamingpb.ReplicatePChannelMeta))
 	})
 	return _c
 }
 
-func (_c *MockReplicateManagerClient_RemoveOutOfTargetReplicators_Call) Return() *MockReplicateManagerClient_RemoveOutOfTargetReplicators_Call {
+func (_c *MockReplicateManagerClient_RemoveOutdatedReplicators_Call) Return() *MockReplicateManagerClient_RemoveOutdatedReplicators_Call {
 	_c.Call.Return()
 	return _c
 }
 
-func (_c *MockReplicateManagerClient_RemoveOutOfTargetReplicators_Call) RunAndReturn(run func([]*streamingpb.ReplicatePChannelMeta)) *MockReplicateManagerClient_RemoveOutOfTargetReplicators_Call {
+func (_c *MockReplicateManagerClient_RemoveOutdatedReplicators_Call) RunAndReturn(run func([]*streamingpb.ReplicatePChannelMeta)) *MockReplicateManagerClient_RemoveOutdatedReplicators_Call {
+	_c.Run(run)
+	return _c
+}
+
+// RemoveReplicator provides a mock function with given fields: replicateInfo
+func (_m *MockReplicateManagerClient) RemoveReplicator(replicateInfo *streamingpb.ReplicatePChannelMeta) {
+	_m.Called(replicateInfo)
+}
+
+// MockReplicateManagerClient_RemoveReplicator_Call is a *mock.Call that shadows Run/Return methods with type explicit version for method 'RemoveReplicator'
+type MockReplicateManagerClient_RemoveReplicator_Call struct {
+	*mock.Call
+}
+
+// RemoveReplicator is a helper method to define mock.On call
+//   - replicateInfo *streamingpb.ReplicatePChannelMeta
+func (_e *MockReplicateManagerClient_Expecter) RemoveReplicator(replicateInfo interface{}) *MockReplicateManagerClient_RemoveReplicator_Call {
+	return &MockReplicateManagerClient_RemoveReplicator_Call{Call: _e.mock.On("RemoveReplicator", replicateInfo)}
+}
+
+func (_c *MockReplicateManagerClient_RemoveReplicator_Call) Run(run func(replicateInfo *streamingpb.ReplicatePChannelMeta)) *MockReplicateManagerClient_RemoveReplicator_Call {
+	_c.Call.Run(func(args mock.Arguments) {
+		run(args[0].(*streamingpb.ReplicatePChannelMeta))
+	})
+	return _c
+}
+
+func (_c *MockReplicateManagerClient_RemoveReplicator_Call) Return() *MockReplicateManagerClient_RemoveReplicator_Call {
+	_c.Call.Return()
+	return _c
+}
+
+func (_c *MockReplicateManagerClient_RemoveReplicator_Call) RunAndReturn(run func(*streamingpb.ReplicatePChannelMeta)) *MockReplicateManagerClient_RemoveReplicator_Call {
 	_c.Run(run)
 	return _c
 }

internal/cdc/replication/replicate_manager_client.go

@@ -23,8 +23,11 @@ type ReplicateManagerClient interface {
 	// CreateReplicator creates a new replicator for the replicate pchannel.
 	CreateReplicator(replicateInfo *streamingpb.ReplicatePChannelMeta)
 
-	// RemoveOutOfTargetReplicators removes replicators that are not in the target replicate pchannels.
-	RemoveOutOfTargetReplicators(targetReplicatePChannels []*streamingpb.ReplicatePChannelMeta)
+	// RemoveReplicator removes a replicator for the replicate pchannel.
+	RemoveReplicator(replicateInfo *streamingpb.ReplicatePChannelMeta)
+
+	// RemoveOutdatedReplicators removes the outdated replicators.
+	RemoveOutdatedReplicators(aliveReplicates []*streamingpb.ReplicatePChannelMeta)
 
 	// Close closes the replicate manager client.
 	Close()

internal/cdc/replication/replicatemanager/replicate_manager.go

@@ -20,7 +20,6 @@ import (
 	"context"
 	"strings"
 
-	"github.com/samber/lo"
 	"go.uber.org/zap"
 
 	"github.com/milvus-io/milvus/internal/metastore/kv/streamingcoord"
@@ -53,7 +52,7 @@ func (r *replicateManager) CreateReplicator(replicateInfo *streamingpb.Replicate
 	)
 	currentClusterID := paramtable.Get().CommonCfg.ClusterPrefix.GetValue()
 	if !strings.Contains(replicateInfo.GetSourceChannelName(), currentClusterID) {
-		// current cluster is not source cluster, skip create replicator
+		// should be checked by controller, here is a redundant check
 		return
 	}
 	replicatorKey := streamingcoord.BuildReplicatePChannelMetaKey(replicateInfo)
@@ -69,17 +68,37 @@ func (r *replicateManager) CreateReplicator(replicateInfo *streamingpb.Replicate
 	logger.Info("created replicator for replicate pchannel")
 }
 
-func (r *replicateManager) RemoveOutOfTargetReplicators(targetReplicatePChannels []*streamingpb.ReplicatePChannelMeta) {
-	targets := lo.KeyBy(targetReplicatePChannels, streamingcoord.BuildReplicatePChannelMetaKey)
+func (r *replicateManager) RemoveReplicator(replicateInfo *streamingpb.ReplicatePChannelMeta) {
+	logger := log.With(
+		zap.String("sourceChannel", replicateInfo.GetSourceChannelName()),
+		zap.String("targetChannel", replicateInfo.GetTargetChannelName()),
+	)
+	replicatorKey := streamingcoord.BuildReplicatePChannelMetaKey(replicateInfo)
+	replicator, ok := r.replicators[replicatorKey]
+	if !ok {
+		logger.Info("replicator not found, skip remove")
+		return
+	}
+	replicator.StopReplicate()
+	delete(r.replicators, replicatorKey)
+	delete(r.replicatorPChannels, replicatorKey)
+	logger.Info("removed replicator for replicate pchannel")
+}
+
+func (r *replicateManager) RemoveOutdatedReplicators(aliveReplicates []*streamingpb.ReplicatePChannelMeta) {
+	alivesMap := make(map[string]struct{})
+	for _, replicate := range aliveReplicates {
+		alivesMap[streamingcoord.BuildReplicatePChannelMetaKey(replicate)] = struct{}{}
+	}
 	for replicatorKey, replicator := range r.replicators {
-		if pchannelMeta, ok := targets[replicatorKey]; !ok {
+		if _, ok := alivesMap[replicatorKey]; !ok {
 			replicator.StopReplicate()
+			info := r.replicatorPChannels[replicatorKey]
 			delete(r.replicators, replicatorKey)
 			delete(r.replicatorPChannels, replicatorKey)
-			log.Info("removed replicator due to out of target",
-				zap.String("sourceChannel", pchannelMeta.GetSourceChannelName()),
-				zap.String("targetChannel", pchannelMeta.GetTargetChannelName()),
-			)
+			log.Info("removed replicator for replicate pchannel",
+				zap.String("sourceChannel", info.GetSourceChannelName()),
+				zap.String("targetChannel", info.GetTargetChannelName()))
 		}
 	}
 }

internal/cdc/resource/resource.go

@@ -19,6 +19,8 @@ package resource
 import (
 	"reflect"
 
+	clientv3 "go.etcd.io/etcd/client/v3"
+
 	"github.com/milvus-io/milvus/internal/cdc/cluster"
 	"github.com/milvus-io/milvus/internal/cdc/controller"
 	"github.com/milvus-io/milvus/internal/cdc/replication"
@@ -39,6 +41,13 @@ func OptMetaKV(metaKV kv.MetaKv) optResourceInit {
 	}
 }
 
+// OptETCD provides the etcd client to the resource.
+func OptETCD(etcd *clientv3.Client) optResourceInit {
+	return func(r *resourceImpl) {
+		r.etcdClient = etcd
+	}
+}
+
 // OptReplicateManagerClient provides the replicate manager client to the resource.
 func OptReplicateManagerClient(replicateManagerClient replication.ReplicateManagerClient) optResourceInit {
 	return func(r *resourceImpl) {
@@ -78,6 +87,7 @@ func Init(opts ...optResourceInit) {
 	newR.clusterClient = cluster.NewClusterClient()
 
 	assertNotNil(newR.MetaKV())
+	assertNotNil(newR.ETCD())
 	assertNotNil(newR.ReplicationCatalog())
 	assertNotNil(newR.ClusterClient())
 	assertNotNil(newR.ReplicateManagerClient())
@@ -97,6 +107,7 @@ func Resource() *resourceImpl {
 // All utility on it is concurrent-safe and singleton.
 type resourceImpl struct {
 	metaKV                 kv.MetaKv
+	etcdClient             *clientv3.Client
 	catalog                metastore.ReplicationCatalog
 	clusterClient          cluster.ClusterClient
 	replicateManagerClient replication.ReplicateManagerClient
@@ -108,6 +119,11 @@ func (r *resourceImpl) MetaKV() kv.MetaKv {
 	return r.metaKV
 }
 
+// ETCD returns the etcd client.
+func (r *resourceImpl) ETCD() *clientv3.Client {
+	return r.etcdClient
+}
+
 // ReplicationCatalog returns the replication catalog.
 func (r *resourceImpl) ReplicationCatalog() metastore.ReplicationCatalog {
 	return r.catalog

internal/cdc/resource/test_utility.go

@@ -6,6 +6,8 @@ package resource
 import (
 	"testing"
 
+	clientv3 "go.etcd.io/etcd/client/v3"
+
 	"github.com/milvus-io/milvus/internal/cdc/cluster"
 	"github.com/milvus-io/milvus/internal/cdc/controller"
 	"github.com/milvus-io/milvus/internal/cdc/replication"
@@ -22,6 +24,9 @@ func InitForTest(t *testing.T, opts ...optResourceInit) {
 	if r.metaKV == nil {
 		r.metaKV = mock_kv.NewMockMetaKv(t)
 	}
+	if r.etcdClient == nil {
+		r.etcdClient = &clientv3.Client{}
+	}
 	if r.catalog == nil {
 		r.catalog = mock_metastore.NewMockReplicationCatalog(t)
 	}

internal/cdc/server.go

@@ -19,6 +19,8 @@ package cdc
 import (
 	"context"
 
+	"go.uber.org/zap"
+
 	"github.com/milvus-io/milvus/internal/cdc/resource"
 	"github.com/milvus-io/milvus/pkg/v2/log"
 )
@@ -42,7 +44,11 @@ func (svr *CDCServer) Init() error {
 
 // Start starts CDCServer.
 func (svr *CDCServer) Start() error {
-	resource.Resource().Controller().Start()
+	err := resource.Resource().Controller().Start()
+	if err != nil {
+		log.Ctx(svr.ctx).Error("start CDC controller failed", zap.Error(err))
+		return err
+	}
 	log.Ctx(svr.ctx).Info("CDCServer start successfully")
 	return nil
 }

internal/distributed/cdc/service.go

@@ -32,14 +32,12 @@ import (
 	"github.com/milvus-io/milvus/internal/cdc/replication/replicatemanager"
 	"github.com/milvus-io/milvus/internal/cdc/resource"
 	etcdkv "github.com/milvus-io/milvus/internal/kv/etcd"
-	tikvkv "github.com/milvus-io/milvus/internal/kv/tikv"
 	"github.com/milvus-io/milvus/internal/util/componentutil"
 	kvfactory "github.com/milvus-io/milvus/internal/util/dependency/kv"
 	"github.com/milvus-io/milvus/pkg/v2/kv"
 	"github.com/milvus-io/milvus/pkg/v2/log"
 	"github.com/milvus-io/milvus/pkg/v2/util"
 	"github.com/milvus-io/milvus/pkg/v2/util/paramtable"
-	"github.com/milvus-io/milvus/pkg/v2/util/tikv"
 	"github.com/milvus-io/milvus/pkg/v2/util/typeutil"
 )
 
@@ -48,7 +46,7 @@ type Server struct {
 	ctx    context.Context
 	cancel context.CancelFunc
 
-	metaKV    kv.MetaKv
+	watchKV   kv.WatchKV
 	cdcServer *cdc.CDCServer
 
 	etcdCli *clientv3.Client
@@ -146,7 +144,8 @@ func (s *Server) init() (err error) {
 	// Create CDC service.
 	s.cdcServer = cdc.NewCDCServer(s.ctx)
 	resource.Init(
-		resource.OptMetaKV(s.metaKV),
+		resource.OptMetaKV(s.watchKV),
+		resource.OptETCD(s.etcdCli),
 		resource.OptReplicateManagerClient(replicatemanager.NewReplicateManager()),
 		resource.OptController(controllerimpl.NewController()),
 	)
@@ -176,18 +175,11 @@ func (s *Server) initMeta() error {
 	log.Info("cdc connecting to metadata store", zap.String("metaType", metaType))
 	metaRootPath := ""
 	if metaType == util.MetaStoreTypeTiKV {
-		var err error
-		s.tikvCli, err = tikv.GetTiKVClient(&paramtable.Get().TiKVCfg)
-		if err != nil {
-			log.Warn("cdc init tikv client failed", zap.Error(err))
-			return err
-		}
-		metaRootPath = params.TiKVCfg.MetaRootPath.GetValue()
-		s.metaKV = tikvkv.NewTiKV(s.tikvCli, metaRootPath,
-			tikvkv.WithRequestTimeout(paramtable.Get().ServiceParam.TiKVCfg.RequestTimeout.GetAsDuration(time.Millisecond)))
+		// TODO: sheep, support watch operation for tikv
+		panic("tikv is not supported for cdc")
 	} else if metaType == util.MetaStoreTypeEtcd {
 		metaRootPath = params.EtcdCfg.MetaRootPath.GetValue()
-		s.metaKV = etcdkv.NewEtcdKV(s.etcdCli, metaRootPath,
+		s.watchKV = etcdkv.NewEtcdKV(s.etcdCli, metaRootPath,
 			etcdkv.WithRequestTimeout(paramtable.Get().ServiceParam.EtcdCfg.RequestTimeout.GetAsDuration(time.Millisecond)))
 	}
 	return nil

pkg/.mockery_pkg.yaml

@@ -8,6 +8,7 @@ packages:
   github.com/milvus-io/milvus/pkg/v2/kv:
     interfaces:
       MetaKv:
+      WatchKV:
   github.com/milvus-io/milvus/pkg/v2/streaming/util/message:
     interfaces:
       MessageID: