@kayousterhout , en , if the DAGScheduler throws some exception during the eventProcessing loop, with this patch, eventProcessingActor will suspend itself, during this process, all messages are queued; and then the supervisor stops the eventProcessingActor, all messages from TM to the eventProcessingActor will be routed to deadLetter Service of ActorSystem (i.e. should be discarded silently) is that right? @markhamstra