diff --git a/common/metrics/defs.go b/common/metrics/defs.go
index 82a01d447dc..f109a40fcba 100644
--- a/common/metrics/defs.go
+++ b/common/metrics/defs.go
@@ -544,6 +544,8 @@ var ScopeDefs = map[ServiceIdx]map[int]scopeDefinition{
 		TimerTaskWorkflowTimeoutScope:              {operation: "TimerTaskWorkflowTimeout"},
 		TimerTaskDeleteHistoryEvent:                {operation: "TimerTaskDeleteHistoryEvent"},
 		HistoryEventNotificationScope:              {operation: "HistoryEventNotification"},
+		ReplicatorQueueProcessorScope:              {operation: "ReplicatorQueueProcessor"},
+		ReplicatorTaskHistoryScope:                 {operation: "ReplicatorTaskHistory"},
 	},
 	// Matching Scope Names
 	Matching: {
diff --git a/service/history/historyBuilder.go b/service/history/historyBuilder.go
index d2f396a65c6..c976ff8a3eb 100644
--- a/service/history/historyBuilder.go
+++ b/service/history/historyBuilder.go
@@ -37,22 +37,19 @@ const (
 
 type (
 	historyBuilder struct {
-		firstEventID int64
-		nextEventID  int64
-		serializer   persistence.HistorySerializer
-		history      []*workflow.HistoryEvent
-		msBuilder    *mutableStateBuilder
-		logger       bark.Logger
+		serializer persistence.HistorySerializer
+		history    []*workflow.HistoryEvent
+		msBuilder  *mutableStateBuilder
+		logger     bark.Logger
 	}
 )
 
 func newHistoryBuilder(msBuilder *mutableStateBuilder, logger bark.Logger) *historyBuilder {
 	return &historyBuilder{
-		firstEventID: msBuilder.GetNextEventID(),
-		serializer:   persistence.NewJSONHistorySerializer(),
-		history:      []*workflow.HistoryEvent{},
-		msBuilder:    msBuilder,
-		logger:       logger.WithField(logging.TagWorkflowComponent, logging.TagValueHistoryBuilderComponent),
+		serializer: persistence.NewJSONHistorySerializer(),
+		history:    []*workflow.HistoryEvent{},
+		msBuilder:  msBuilder,
+		logger:     logger.WithField(logging.TagWorkflowComponent, logging.TagValueHistoryBuilderComponent),
 	}
 }
 
@@ -419,7 +416,6 @@ func (b *historyBuilder) AddChildWorkflowExecutionTimedOutEvent(domain *string,
 
 func (b *historyBuilder) addEventToHistory(event *workflow.HistoryEvent) *workflow.HistoryEvent {
 	b.history = append(b.history, event)
-	b.nextEventID = b.msBuilder.GetNextEventID() // Keep track of nextEventID for generating replication task
 	return event
 }
 
diff --git a/service/history/historyEngine.go b/service/history/historyEngine.go
index 5c946f504bc..dfda1c39f8e 100644
--- a/service/history/historyEngine.go
+++ b/service/history/historyEngine.go
@@ -288,8 +288,8 @@ func (e *historyEngineImpl) StartWorkflowExecution(startRequest *h.StartWorkflow
 		}
 
 		replicationTask := &persistence.HistoryReplicationTask{
-			FirstEventID:        msBuilder.hBuilder.firstEventID,
-			NextEventID:         msBuilder.hBuilder.nextEventID,
+			FirstEventID:        firstEventID,
+			NextEventID:         msBuilder.GetNextEventID(),
 			Version:             failoverVersion,
 			LastReplicationInfo: nil,
 		}
diff --git a/service/history/mutableStateBuilder.go b/service/history/mutableStateBuilder.go
index 3aedb2f47e8..8903f5ec064 100644
--- a/service/history/mutableStateBuilder.go
+++ b/service/history/mutableStateBuilder.go
@@ -234,7 +234,7 @@ func (e *mutableStateBuilder) ApplyReplicationStateUpdates(failoverVersion int64
 	e.replicationState.CurrentVersion = failoverVersion
 	e.replicationState.LastWriteVersion = failoverVersion
 	// TODO: Rename this to NextEventID to stay consistent naming convention with rest of code base
-	e.replicationState.LastWriteEventID = e.hBuilder.nextEventID - 1
+	e.replicationState.LastWriteEventID = e.GetNextEventID() - 1
 }
 
 func (e *mutableStateBuilder) CloseUpdateSession(createReplicationTask bool) (*mutableStateSessionUpdates, error) {
@@ -291,8 +291,8 @@ func (e *mutableStateBuilder) CloseUpdateSession(createReplicationTask bool) (*m
 
 func (e *mutableStateBuilder) createReplicationTask() *persistence.HistoryReplicationTask {
 	return &persistence.HistoryReplicationTask{
-		FirstEventID:        e.hBuilder.firstEventID,
-		NextEventID:         e.hBuilder.nextEventID,
+		FirstEventID:        e.GetLastFirstEventID(),
+		NextEventID:         e.GetNextEventID(),
 		Version:             e.replicationState.CurrentVersion,
 		LastReplicationInfo: e.replicationState.LastReplicationInfo,
 	}
@@ -1644,8 +1644,8 @@ func (e *mutableStateBuilder) AddContinueAsNewEvent(decisionCompletedEventID int
 		}
 
 		replicationTask := &persistence.HistoryReplicationTask{
-			FirstEventID:        newStateBuilder.hBuilder.firstEventID,
-			NextEventID:         newStateBuilder.hBuilder.nextEventID,
+			FirstEventID:        firstEventID,
+			NextEventID:         newStateBuilder.GetNextEventID(),
 			Version:             failoverVersion,
 			LastReplicationInfo: nil,
 		}