updates mu name, adds comment

worker/pkg/workflows/datasync/activities/sync/activity.go

@@ -106,7 +106,8 @@ func (a *Activity) getTunnelManagerByRunId(wfId, runId string) (connectiontunnel
 }
 
 var (
-	benthosStreamMu sync.Mutex
+	// Hack that locks the instanced bento stream builder build step that causes data races if done in parallel
+	streamBuilderMu sync.Mutex
 )
 
 // Temporal activity that runs benthos and syncs a source connection to one or more destination connections
@@ -242,7 +243,7 @@ func (a *Activity) Sync(ctx context.Context, req *SyncRequest, metadata *SyncMet
 	envKeyMap["TEMPORAL_WORKFLOW_ID"] = info.WorkflowExecution.ID
 	envKeyMap["TEMPORAL_RUN_ID"] = info.WorkflowExecution.RunID
 
-	benthosStreamMu.Lock()
+	streamBuilderMu.Lock()
 	streambldr := benthosenv.NewStreamBuilder()
 	// would ideally use the activity logger here but can't convert it into a slog.
 	streambldr.SetLogger(slogger.With(
@@ -254,12 +255,12 @@ func (a *Activity) Sync(ctx context.Context, req *SyncRequest, metadata *SyncMet
 
 	err = streambldr.SetYAML(req.BenthosConfig)
 	if err != nil {
-		benthosStreamMu.Unlock()
+		streamBuilderMu.Unlock()
 		return nil, fmt.Errorf("unable to convert benthos config to yaml for stream builder: %w", err)
 	}
 
 	stream, err := a.benthosStreamManager.NewBenthosStreamFromBuilder(streambldr)
-	benthosStreamMu.Unlock()
+	streamBuilderMu.Unlock()
 	if err != nil {
 		return nil, fmt.Errorf("unable to build benthos config: %w", err)
 	}