Ah, now I see what you mean. You are right. Thanks for reporting. Please create an issue <https://github.com/akka/akka/issues/new>. If you are interested in contributing a pull request would be great.
/Patrik On Fri, Nov 20, 2015 at 2:25 PM, Andrzej Dębski <andrzejdebsk...@gmail.com> wrote: > I think it just postpones the problem - you could have the same sequence > of events: Subscribe to mediator in the same time as scheduler puts Prune > message in topic actor mailbox, mediator doesn't see topic actor as dead so > Subscribe message is forwarded, Prune is processed and context.stop(self) > is invoked in topic actor stopping it immidietly, also in docs of > context.stop(self) it says that "If this method is applied to the `self` > reference from inside an Actor then that Actor is guaranteed to not process > any further messages after this call;" > > W dniu piątek, 20 listopada 2015 13:48:37 UTC+1 użytkownik Patrik Nordwall > napisał: >> >> The topic actors don’t stop themselves immediately. For efficiency >> reasons they stay around for a while even when there is no subscribers. See >> pruneDeadline in the code. >> >> Doesn’t that take care of this also? >> >> Cheers, >> Patrik >> >> >> On Fri, Nov 20, 2015 at 12:36 PM, Andrzej Dębski <andrzej...@gmail.com> >> wrote: >> >>> 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+...@googlegroups.com. >>> To post to this group, send email to akka...@googlegroups.com. >>> Visit this group at http://groups.google.com/group/akka-user. >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> >> >> -- >> >> Patrik Nordwall >> Typesafe <http://typesafe.com/> - Reactive apps on the JVM >> Twitter: @patriknw >> >> -- > >>>>>>>>>> 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. > -- Patrik Nordwall Typesafe <http://typesafe.com/> - Reactive apps on the JVM Twitter: @patriknw -- >>>>>>>>>> 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. 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