I was looking through DistributedPubSub code and I was wondering about possible problem due to how topic/children actors are managed.
When new subscriber arrive for given topic the child/topic actor is looked up using context.child(encTopic), if actor exists message is forwarded, if not the child actor is created, registered in "registry" and then message is forwarded. Topic actors stop themselves when all their subscribers are either terminated (death watch by topic actor on subscriber) or they just unsubscribe themselves from the topic. Could there be a situation where 1. Subscribe message is sent to mediator from SubscriberA 2. At the same time SubscriberB is terminated and this message arrives to topic actor. 3. Topic actor stops itself using context.stop(self) 4. At the same time parent/mediator actor performs lookup of child and decided that topic actor is alive and forwards him Subscribe message 5. Subscribe message goes to dead letters because topic actor is already dead, mediator does not inform subscriber that something went wrong and/or do not try to retry sending Subscribe message to new version of topic actor. According to http://stackoverflow.com/questions/23629159/get-or-create-child-akka-actor-and-ensure-liveness the solution would be to send kind-of Terminated message to mediator so Subscribe and Terminated messages are processed serially, also watching out for the fact that stopping actor is async operation so even if we invoke context.stop(child) from context of parent there is no guarantee that path is immediately. Maybe the semantics of termination/death-watch/child-lookup are a bit different from general ones due to the fact that here we are discussing about actors that reside in the same JVM but I would like to know if this is genuine problem or I just missed something when reading the code. -- >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>>>>> Check the FAQ: >>>>>>>>>> http://doc.akka.io/docs/akka/current/additional/faq.html >>>>>>>>>> Search the archives: https://groups.google.com/group/akka-user --- You received this message because you are subscribed to the Google Groups "Akka User List" group. To unsubscribe from this group and stop receiving emails from it, send an email to akka-user+unsubscr...@googlegroups.com. To post to this group, send email to akka-user@googlegroups.com. Visit this group at http://groups.google.com/group/akka-user. For more options, visit https://groups.google.com/d/optout.
