*: port sink flow control for old processor & new processor to releas…

…e-5.0 (#1840)

cdc/metrics_processor.go

@@ -82,6 +82,13 @@ var (
 			Name:      "exit_with_error_count",
 			Help:      "counter for processor exits with error",
 		}, []string{"changefeed", "capture"})
+	tableMemoryGauge = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Namespace: "ticdc",
+			Subsystem: "processor",
+			Name:      "table_memory_consumption",
+			Help:      "estimated memory consumption for a table after the sorter",
+		}, []string{"changefeed", "capture", "table"})
 )
 
 // initProcessorMetrics registers all metrics used in processor
@@ -95,4 +102,5 @@ func initProcessorMetrics(registry *prometheus.Registry) {
 	registry.MustRegister(txnCounter)
 	registry.MustRegister(updateInfoDuration)
 	registry.MustRegister(processorErrorCounter)
+	registry.MustRegister(tableMemoryGauge)
 }

cdc/processor.go

@@ -34,6 +34,8 @@ import (
 	"github.com/pingcap/ticdc/cdc/puller"
 	psorter "github.com/pingcap/ticdc/cdc/puller/sorter"
 	"github.com/pingcap/ticdc/cdc/sink"
+	"github.com/pingcap/ticdc/cdc/sink/common"
+	serverConfig "github.com/pingcap/ticdc/pkg/config"
 	cerror "github.com/pingcap/ticdc/pkg/errors"
 	"github.com/pingcap/ticdc/pkg/filter"
 	"github.com/pingcap/ticdc/pkg/notify"
@@ -58,6 +60,11 @@ const (
 	defaultSyncResolvedBatch = 1024
 
 	schemaStorageGCLag = time.Minute * 20
+
+	// for better sink performance under flow control
+	resolvedTsInterpolateInterval = 200 * time.Millisecond
+	flushMemoryMetricsDuration    = time.Second * 5
+	flowControlOutChSize          = 128
 )
 
 type oldProcessor struct {
@@ -919,7 +926,117 @@ func (p *oldProcessor) addTable(ctx context.Context, tableID int64, replicaInfo
 	syncTableNumGauge.WithLabelValues(p.changefeedID, p.captureInfo.AdvertiseAddr).Inc()
 }
 
-const maxLagWithCheckpointTs = (30 * 1000) << 18 // 30s
+// runFlowControl controls the flow of events out of the sorter.
+func (p *oldProcessor) runFlowControl(
+	ctx context.Context,
+	tableID model.TableID,
+	flowController *common.TableFlowController,
+	inCh <-chan *model.PolymorphicEvent,
+	outCh chan<- *model.PolymorphicEvent) {
+	var (
+		lastSendResolvedTsTime       time.Time
+		lastCRTs, lastSentResolvedTs uint64
+	)
+
+	for {
+		select {
+		case <-ctx.Done():
+			// NOTE: This line is buggy, because `context.Canceled` may indicate an actual error.
+			// TODO Will be resolved together with other similar problems.
+			if errors.Cause(ctx.Err()) != context.Canceled {
+				p.sendError(ctx.Err())
+			}
+			return
+		case event, ok := <-inCh:
+			if !ok {
+				// sorter output channel has been closed.
+				// The sorter must have exited and has a reportable exit reason,
+				// so we don't need to worry about sending an error here.
+				log.Info("sorter output channel closed",
+					zap.Int64("tableID", tableID), util.ZapFieldChangefeed(ctx))
+				return
+			}
+
+			if event == nil || event.RawKV == nil {
+				// This is an invariant violation.
+				log.Panic("unexpected empty event", zap.Reflect("event", event))
+			}
+
+			if event.RawKV.OpType != model.OpTypeResolved {
+				size := uint64(event.RawKV.ApproximateSize())
+				commitTs := event.CRTs
+				// We interpolate a resolved-ts if none has been sent for some time.
+				if time.Since(lastSendResolvedTsTime) > resolvedTsInterpolateInterval {
+					// Refer to `cdc/processor/pipeline/sorter.go` for detailed explanation of the design.
+					// This is a backport.
+					if lastCRTs > lastSentResolvedTs && commitTs > lastCRTs {
+						lastSentResolvedTs = lastCRTs
+						lastSendResolvedTsTime = time.Now()
+						interpolatedEvent := model.NewResolvedPolymorphicEvent(0, lastCRTs)
+
+						select {
+						case <-ctx.Done():
+							// TODO fix me
+							if errors.Cause(ctx.Err()) != context.Canceled {
+								p.sendError(ctx.Err())
+							}
+							return
+						case outCh <- interpolatedEvent:
+						}
+					}
+				}
+				// NOTE we allow the quota to be exceeded if blocking means interrupting a transaction.
+				// Otherwise the pipeline would deadlock.
+				err := flowController.Consume(commitTs, size, func() error {
+					if lastCRTs > lastSentResolvedTs {
+						// If we are blocking, we send a Resolved Event here to elicit a sink-flush.
+						// Not sending a Resolved Event here will very likely deadlock the pipeline.
+						// NOTE: This is NOT an optimization, but is for liveness.
+						lastSentResolvedTs = lastCRTs
+						lastSendResolvedTsTime = time.Now()
+
+						msg := model.NewResolvedPolymorphicEvent(0, lastCRTs)
+						select {
+						case <-ctx.Done():
+							return ctx.Err()
+						case outCh <- msg:
+						}
+					}
+					return nil
+				})
+				if err != nil {
+					log.Error("flow control error", zap.Error(err))
+					if cerror.ErrFlowControllerAborted.Equal(err) {
+						log.Info("flow control cancelled for table",
+							zap.Int64("tableID", tableID),
+							util.ZapFieldChangefeed(ctx))
+					} else {
+						p.sendError(ctx.Err())
+					}
+					return
+				}
+				lastCRTs = commitTs
+			} else {
+				// handle OpTypeResolved
+				if event.CRTs < lastSentResolvedTs {
+					continue
+				}
+				lastSentResolvedTs = event.CRTs
+				lastSendResolvedTsTime = time.Now()
+			}
+
+			select {
+			case <-ctx.Done():
+				// TODO fix me
+				if errors.Cause(ctx.Err()) != context.Canceled {
+					p.sendError(ctx.Err())
+				}
+				return
+			case outCh <- event:
+			}
+		}
+	}
+}
 
 // sorterConsume receives sorted PolymorphicEvent from sorter of each table and
 // sends to processor's output chan
@@ -933,7 +1050,7 @@ func (p *oldProcessor) sorterConsume(
 	replicaInfo *model.TableReplicaInfo,
 	sink sink.Sink,
 ) {
-	var lastResolvedTs, lastCheckPointTs uint64
+	var lastResolvedTs uint64
 	opDone := false
 	resolvedTsGauge := tableResolvedTsGauge.WithLabelValues(p.changefeedID, p.captureInfo.AdvertiseAddr, tableName)
 	checkDoneTicker := time.NewTicker(1 * time.Second)
@@ -1022,6 +1139,19 @@ func (p *oldProcessor) sorterConsume(
 	}
 	defer globalResolvedTsReceiver.Stop()
 
+	perTableMemoryQuota := serverConfig.GetGlobalServerConfig().PerTableMemoryQuota
+	log.Debug("creating table flow controller",
+		zap.String("table-name", tableName),
+		zap.Int64("table-id", tableID),
+		zap.Uint64("quota", perTableMemoryQuota),
+		util.ZapFieldChangefeed(ctx))
+
+	flowController := common.NewTableFlowController(perTableMemoryQuota)
+	defer func() {
+		flowController.Abort()
+		tableMemoryGauge.DeleteLabelValues(p.changefeedID, p.captureInfo.AdvertiseAddr, tableName)
+	}()
+
 	sendResolvedTs2Sink := func() error {
 		localResolvedTs := atomic.LoadUint64(&p.localResolvedTs)
 		globalResolvedTs := atomic.LoadUint64(&p.globalResolvedTs)
@@ -1044,52 +1174,43 @@ func (p *oldProcessor) sorterConsume(
 			}
 			return err
 		}
-		lastCheckPointTs = checkpointTs
 
 		if checkpointTs < replicaInfo.StartTs {
 			checkpointTs = replicaInfo.StartTs
 		}
 
 		if checkpointTs != 0 {
 			atomic.StoreUint64(pCheckpointTs, checkpointTs)
+			flowController.Release(checkpointTs)
 			p.localCheckpointTsNotifier.Notify()
 		}
 		return nil
 	}
+
+	flowControlOutCh := make(chan *model.PolymorphicEvent, flowControlOutChSize)
+	go func() {
+		p.runFlowControl(ctx, tableID, flowController, sorter.Output(), flowControlOutCh)
+		close(flowControlOutCh)
+	}()
+
+	metricsTableMemoryGauge := tableMemoryGauge.WithLabelValues(p.changefeedID, p.captureInfo.AdvertiseAddr, tableName)
+	metricsTicker := time.NewTicker(flushMemoryMetricsDuration)
+	defer metricsTicker.Stop()
+
 	for {
 		select {
 		case <-ctx.Done():
 			if errors.Cause(ctx.Err()) != context.Canceled {
 				p.sendError(ctx.Err())
 			}
 			return
-		case pEvent := <-sorter.Output():
+		case <-metricsTicker.C:
+			metricsTableMemoryGauge.Set(float64(flowController.GetConsumption()))
+		case pEvent := <-flowControlOutCh:
 			if pEvent == nil {
 				continue
 			}
 
-			for lastResolvedTs > maxLagWithCheckpointTs+lastCheckPointTs {
-				log.Debug("the lag between local checkpoint Ts and local resolved Ts is too lang",
-					zap.Uint64("resolvedTs", lastResolvedTs), zap.Uint64("lastCheckPointTs", lastCheckPointTs),
-					zap.Int64("tableID", tableID), util.ZapFieldChangefeed(ctx))
-				select {
-				case <-ctx.Done():
-					if ctx.Err() != context.Canceled {
-						p.sendError(errors.Trace(ctx.Err()))
-					}
-					return
-				case <-globalResolvedTsReceiver.C:
-					if err := sendResolvedTs2Sink(); err != nil {
-						// error is already sent to processor, so we can just ignore it
-						return
-					}
-				case <-checkDoneTicker.C:
-					if !opDone {
-						checkDone()
-					}
-				}
-			}
-
 			pEvent.SetUpFinishedChan()
 			select {
 			case <-ctx.Done():

cdc/processor/pipeline/metrics.go

@@ -32,10 +32,18 @@ var (
 			Name:      "txn_count",
 			Help:      "txn count received/executed by this processor",
 		}, []string{"type", "changefeed", "capture"})
+	tableMemoryGauge = prometheus.NewGaugeVec(
+		prometheus.GaugeOpts{
+			Namespace: "ticdc",
+			Subsystem: "processor",
+			Name:      "table_memory_consumption",
+			Help:      "estimated memory consumption for a table after the sorter",
+		}, []string{"changefeed", "capture", "table"})
 )
 
 // InitMetrics registers all metrics used in processor
 func InitMetrics(registry *prometheus.Registry) {
 	registry.MustRegister(tableResolvedTsGauge)
 	registry.MustRegister(txnCounter)
+	registry.MustRegister(tableMemoryGauge)
 }

cdc/processor/pipeline/sink.go

@@ -72,16 +72,20 @@ type sinkNode struct {
 
 	eventBuffer []*model.PolymorphicEvent
 	rowBuffer   []*model.RowChangedEvent
+
+	flowController tableFlowController
 }
 
-func newSinkNode(sink sink.Sink, startTs model.Ts, targetTs model.Ts) *sinkNode {
+func newSinkNode(sink sink.Sink, startTs model.Ts, targetTs model.Ts, flowController tableFlowController) *sinkNode {
 	return &sinkNode{
 		sink:         sink,
 		status:       TableStatusInitializing,
 		targetTs:     targetTs,
 		resolvedTs:   startTs,
 		checkpointTs: startTs,
 		barrierTs:    startTs,
+
+		flowController: flowController,
 	}
 }
 
@@ -130,6 +134,8 @@ func (n *sinkNode) flushSink(ctx pipeline.NodeContext, resolvedTs model.Ts) (err
 		return nil
 	}
 	atomic.StoreUint64(&n.checkpointTs, checkpointTs)
+
+	n.flowController.Release(checkpointTs)
 	return nil
 }
 
@@ -216,5 +222,6 @@ func (n *sinkNode) Receive(ctx pipeline.NodeContext) error {
 
 func (n *sinkNode) Destroy(ctx pipeline.NodeContext) error {
 	n.status.store(TableStatusStopped)
+	n.flowController.Abort()
 	return n.sink.Close()
 }

cdc/processor/pipeline/sink_test.go

@@ -36,6 +36,24 @@ type mockSink struct {
 	}
 }
 
+// mockFlowController is created because a real tableFlowController cannot be used
+// we are testing sinkNode by itself.
+type mockFlowController struct{}
+
+func (c *mockFlowController) Consume(commitTs uint64, size uint64, blockCallBack func() error) error {
+	return nil
+}
+
+func (c *mockFlowController) Release(resolvedTs uint64) {
+}
+
+func (c *mockFlowController) Abort() {
+}
+
+func (c *mockFlowController) GetConsumption() uint64 {
+	return 0
+}
+
 func (s *mockSink) Initialize(ctx stdContext.Context, tableInfo []*model.SimpleTableInfo) error {
 	return nil
 }
@@ -90,7 +108,7 @@ func (s *outputSuite) TestStatus(c *check.C) {
 	ctx := context.NewContext(stdContext.Background(), &context.Vars{})
 
 	// test stop at targetTs
-	node := newSinkNode(&mockSink{}, 0, 10)
+	node := newSinkNode(&mockSink{}, 0, 10, &mockFlowController{})
 	c.Assert(node.Init(pipeline.MockNodeContext4Test(ctx, nil, nil)), check.IsNil)
 	c.Assert(node.Status(), check.Equals, TableStatusInitializing)
 
@@ -116,7 +134,7 @@ func (s *outputSuite) TestStatus(c *check.C) {
 	c.Assert(node.CheckpointTs(), check.Equals, uint64(10))
 
 	// test the stop at ts command
-	node = newSinkNode(&mockSink{}, 0, 10)
+	node = newSinkNode(&mockSink{}, 0, 10, &mockFlowController{})
 	c.Assert(node.Init(pipeline.MockNodeContext4Test(ctx, nil, nil)), check.IsNil)
 	c.Assert(node.Status(), check.Equals, TableStatusInitializing)
 
@@ -138,7 +156,7 @@ func (s *outputSuite) TestStatus(c *check.C) {
 	c.Assert(node.CheckpointTs(), check.Equals, uint64(6))
 
 	// test the stop at ts command is after then resolvedTs and checkpointTs is greater than stop ts
-	node = newSinkNode(&mockSink{}, 0, 10)
+	node = newSinkNode(&mockSink{}, 0, 10, &mockFlowController{})
 	c.Assert(node.Init(pipeline.MockNodeContext4Test(ctx, nil, nil)), check.IsNil)
 	c.Assert(node.Status(), check.Equals, TableStatusInitializing)
 
@@ -164,7 +182,7 @@ func (s *outputSuite) TestManyTs(c *check.C) {
 	defer testleak.AfterTest(c)()
 	ctx := context.NewContext(stdContext.Background(), &context.Vars{})
 	sink := &mockSink{}
-	node := newSinkNode(sink, 0, 10)
+	node := newSinkNode(sink, 0, 10, &mockFlowController{})
 	c.Assert(node.Init(pipeline.MockNodeContext4Test(ctx, nil, nil)), check.IsNil)
 	c.Assert(node.Status(), check.Equals, TableStatusInitializing)