fix: streamingnode get stucked when stop (#42501)

issue: #42498

- fix: sealed segment cannot be flushed after upgrading
- fix: get mvcc panic when upgrading
- ignore the L0 segment when graceful stop of querynode.

---------

Signed-off-by: chyezh <chyezh@outlook.com>

configs/milvus.yaml

@@ -1204,6 +1204,9 @@ streaming:
     # It's ok to set it into duration string, such as 30s or 1m30s, see time.ParseDuration
     backoffInitialInterval: 50ms
     backoffMultiplier: 2 # The multiplier of balance task trigger backoff, 2 by default
+    # The timeout of wal balancer operation, 10s by default.
+    # If the operation exceeds this timeout, it will be canceled.
+    operationTimeout: 10s
     balancePolicy:
       name: vchannelFair # The multiplier of balance task trigger backoff, 2 by default
       vchannelFair:

internal/datacoord/handler.go

@@ -79,8 +79,8 @@ func (h *ServerHandler) GetDataVChanPositions(channel RWChannel, partitionID Uni
 	)
 	for _, s := range segments {
 		if (partitionID > allPartitionID && s.PartitionID != partitionID) ||
-			(s.GetState() != commonpb.SegmentState_Growing && s.GetStartPosition() == nil && s.GetDmlPosition() == nil) {
-			// empty growing segment don't have dml position and start position
+			((s.GetState() != commonpb.SegmentState_Growing && s.GetState() != commonpb.SegmentState_Sealed) && s.GetStartPosition() == nil && s.GetDmlPosition() == nil) {
+			// empty growing and sealed segment don't have dml position and start position
 			// and it should be recovered for streamingnode, so we add the state-filter here.
 			continue
 		}

internal/querynodev2/server.go

@@ -562,6 +562,9 @@ func (node *QueryNode) Stop() error {
 				if node.pipelineManager != nil {
 					channelNum = node.pipelineManager.Num()
 				}
+				if len(sealedSegments) == 0 && len(growingSegments) == 0 && channelNum == 0 {
+					break outer
+				}
 
 				select {
 				case <-timeoutCh:

internal/streamingcoord/server/balancer/balancer_impl.go

@@ -315,13 +315,16 @@ func (b *balancerImpl) applyBalanceResultToStreamingNode(ctx context.Context, mo
 
 	// different channel can be execute concurrently.
 	g, _ := errgroup.WithContext(ctx)
+	opTimeout := paramtable.Get().StreamingCfg.WALBalancerOperationTimeout.GetAsDurationByParse()
 	// generate balance operations and applied them.
 	for _, channel := range modifiedChannels {
 		channel := channel
 		g.Go(func() error {
 			// all history channels should be remove from related nodes.
 			for _, assignment := range channel.AssignHistories() {
-				if err := resource.Resource().StreamingNodeManagerClient().Remove(ctx, assignment); err != nil {
+				opCtx, cancel := context.WithTimeout(ctx, opTimeout)
+				defer cancel()
+				if err := resource.Resource().StreamingNodeManagerClient().Remove(opCtx, assignment); err != nil {
 					b.Logger().Warn("fail to remove channel", zap.String("assignment", assignment.String()), zap.Error(err))
 					return err
 				}
@@ -329,7 +332,9 @@ func (b *balancerImpl) applyBalanceResultToStreamingNode(ctx context.Context, mo
 			}
 
 			// assign the channel to the target node.
-			if err := resource.Resource().StreamingNodeManagerClient().Assign(ctx, channel.CurrentAssignment()); err != nil {
+			opCtx, cancel := context.WithTimeout(ctx, opTimeout)
+			defer cancel()
+			if err := resource.Resource().StreamingNodeManagerClient().Assign(opCtx, channel.CurrentAssignment()); err != nil {
 				b.Logger().Warn("fail to assign channel", zap.String("assignment", channel.CurrentAssignment().String()), zap.Error(err))
 				return err
 			}

internal/streamingnode/client/handler/handler_client.go

@@ -31,6 +31,7 @@ var (
 	_                           HandlerClient = (*handlerClientImpl)(nil)
 	ErrClientClosed                           = errors.New("handler client is closed")
 	ErrClientAssignmentNotReady               = errors.New("handler client assignment not ready")
+	ErrReadOnlyWAL                            = errors.New("wal is read only")
 )
 
 type (

internal/streamingnode/client/handler/handler_client_impl.go

@@ -59,6 +59,9 @@ func (hc *handlerClientImpl) GetLatestMVCCTimestampIfLocal(ctx context.Context,
 	if err != nil {
 		return 0, err
 	}
+	if w.Channel().AccessMode != types.AccessModeRW {
+		return 0, ErrReadOnlyWAL
+	}
 	return w.GetLatestMVCCTimestamp(ctx, vchannel)
 }
 

internal/streamingnode/server/walmanager/wal_lifetime.go

@@ -93,6 +93,7 @@ func (w *walLifetime) Close() {
 	logger := log.With(zap.String("current", toStateString(currentState)))
 	if oldWAL := currentState.GetWAL(); oldWAL != nil {
 		oldWAL.Close()
+		w.statePair.SetCurrentState(newUnavailableCurrentState(currentState.Term(), nil))
 		logger.Info("close current term wal done at wal life time close")
 	}
 	logger.Info("wal lifetime closed")

pkg/util/paramtable/component_param.go

@@ -5572,6 +5572,7 @@ type streamingConfig struct {
 	WALBalancerTriggerInterval        ParamItem `refreshable:"true"`
 	WALBalancerBackoffInitialInterval ParamItem `refreshable:"true"`
 	WALBalancerBackoffMultiplier      ParamItem `refreshable:"true"`
+	WALBalancerOperationTimeout       ParamItem `refreshable:"true"`
 
 	// balancer Policy
 	WALBalancerPolicyName                           ParamItem `refreshable:"true"`
@@ -5637,6 +5638,15 @@ It's ok to set it into duration string, such as 30s or 1m30s, see time.ParseDura
 		Export:       true,
 	}
 	p.WALBalancerBackoffMultiplier.Init(base.mgr)
+	p.WALBalancerOperationTimeout = ParamItem{
+		Key:     "streaming.walBalancer.operationTimeout",
+		Version: "2.6.0",
+		Doc: `The timeout of wal balancer operation, 10s by default.
+If the operation exceeds this timeout, it will be canceled.`,
+		DefaultValue: "10s",
+		Export:       true,
+	}
+	p.WALBalancerOperationTimeout.Init(base.mgr)
 
 	p.WALBalancerPolicyName = ParamItem{
 		Key:          "streaming.walBalancer.balancePolicy.name",

pkg/util/paramtable/component_param_test.go

@@ -628,6 +628,7 @@ func TestComponentParam(t *testing.T) {
 		assert.Equal(t, 0.01, params.StreamingCfg.WALBalancerPolicyVChannelFairAntiAffinityWeight.GetAsFloat())
 		assert.Equal(t, 0.01, params.StreamingCfg.WALBalancerPolicyVChannelFairRebalanceTolerance.GetAsFloat())
 		assert.Equal(t, 3, params.StreamingCfg.WALBalancerPolicyVChannelFairRebalanceMaxStep.GetAsInt())
+		assert.Equal(t, 10*time.Second, params.StreamingCfg.WALBalancerOperationTimeout.GetAsDurationByParse())
 		assert.Equal(t, 1.0, params.StreamingCfg.WALBroadcasterConcurrencyRatio.GetAsFloat())
 		assert.Equal(t, 10*time.Second, params.StreamingCfg.TxnDefaultKeepaliveTimeout.GetAsDurationByParse())
 		assert.Equal(t, 30*time.Second, params.StreamingCfg.WALWriteAheadBufferKeepalive.GetAsDurationByParse())