On Friday, February 28, 2014 12:27:28 AM UTC-10, rkuhn wrote: > > > 28 feb 2014 kl. 02:40 skrev Jim Newsham <[email protected] <javascript:> > >: > > > Hi Endre thanks for your reply, I appreciate it. After thinking about it > carefully, it makes complete sense. > > I had a longer response and follow-up question, but it was summarily > deleted (by a moderator?). I'm assuming that was in error... > > > It might not always seem like it, but akka-user is manually moderated (to > counter the spam-bots; AFAIK we never rejected a mail from a real human > being). Sometimes it takes a few minutes for a post to be approved, and if > you are really unlucky we might all sleep at the same time. > > Thanks Roland. It actually seems like a glitch in google groups, as the messages still appeared deleted to me, after waiting a day. In case anyone else experiences this: I tried on a different machine and the messages were visible. Coming back to my workstation I logged out of Google and logged in again, and the messages were visible. Strange.
Thanks, Jim Regards, > > Roland > > > Thanks again, > Jim > > > On Tuesday, February 25, 2014 2:02:09 AM UTC-10, Akka Team wrote: >> >> Hi Jim, >> >> >> On Tue, Feb 25, 2014 at 12:02 AM, Jim Newsham <[email protected]> wrote: >> >>> >>> Hi everyone, >>> >>> I just became aware of how Akka can establish a quarantine between >>> remote actor systems, requiring a restart of one of the actor systems. I >>> know this has already been discussed in several threads in this forum, as >>> I've been searching and reading anything relevant to get an understanding >>> of the issues. >>> >>> I apologize for beating a dead horse, but something feels very wrong to >>> me about this approach. It seems very heavy-handed to have a commonly >>> occurring condition where an entire actor system must be restarted. >>> >> >> To answer in short, the fallacy in the above sentence is to state that >> quarantining happens in commonly occurring conditions. It happens only on >> two kinds of occasions: >> - Irrecoverable conditions due to system messages being undeliverable >> for a very long time (and I mean really long), or system message sequence >> numbers are in an inconsistent state on the two systems. >> - An irreversible decision has been made by declaring the other system >> dead (hence the name DeathWatch and not TemporalUnreachabilityWatch and >> cluster node Down instead of cluster node Unreachable) >> >> >>> And it seems contrary to Akka's otherwise fine-grained error handling >>> and recovery support which allows for individual actors to fail and be >>> restarted. >>> >> >> Akka recovers lost connections on the remoting level, and recovers >> cluster node unreachability on the cluster level (main feature of 2.3). >> Quarantining triggers on stronger conditions than those above. >> >> Also, actors that have sent a Terminated are definitely stopped. >> Restart does not send Terminated. >> >> >>> >>> Is quarantining the only reasonable approach? I understand that after a >>> remote actor system is declared unreachable >>> >> >> Not unreachable, this is the point where the argument is invalid. The >> remote system is considered dead. That is an irreversible decision. If you >> want to track temporary unreachability you have to either implement >> heartbeating (if you use pure remoting) or just use the cluster >> unreachability tracking facility. >> >> I hope this clarifies the decision. Also, you might want to take a look >> at this: >> http://doc.akka.io/docs/akka/2.3.0-RC4/scala/remoting.html#Lifecycle_and_Failure_Recovery_Model >> >> -Endre >> >> >>> and Terminated messages are dispatched for remotely watched actors, that >>> we don't want to receive any more messages from the actors which have been >>> declared Terminated. >>> >>> As an alternative idea, what if you included an identifier for the >>> current remote association as part of a remote actor's identifier? In this >>> case, when a new remote association is established, all actors on the >>> remote side are considered distinct from any actors the local side may have >>> communicated with in the past. This guarantees we don't violate the "no >>> messages after Terminated" rule, and allows the distributed system to >>> continue operating without a restart. Individual actors can look up and >>> re-establish communication with their remote peers, achieving fine-grained >>> fault tolerance. >>> >>> Best regards, >>> Jim >>> >>> >>> -- >>> >>>>>>>>>> Read the docs: http://akka.io/docs/ >>> >>>>>>>>>> Check the FAQ: http://akka.io/faq/ >>> >>>>>>>>>> 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 [email protected]. >>> To post to this group, send email to [email protected]. >>> Visit this group at http://groups.google.com/group/akka-user. >>> For more options, visit https://groups.google.com/groups/opt_out. >>> >> >> >> >> -- >> Akka Team >> Typesafe - The software stack for applications that scale >> Blog: letitcrash.com >> Twitter: @akkateam >> > > -- > >>>>>>>>>> Read the docs: http://akka.io/docs/ > >>>>>>>>>> Check the FAQ: http://akka.io/faq/ > >>>>>>>>>> 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 [email protected] <javascript:>. > To post to this group, send email to [email protected]<javascript:> > . > Visit this group at http://groups.google.com/group/akka-user. > For more options, visit https://groups.google.com/groups/opt_out. > > > > > *Dr. Roland Kuhn* > *Akka Tech Lead* > Typesafe <http://typesafe.com/> – Reactive apps on the JVM. > twitter: @rolandkuhn > <http://twitter.com/#!/rolandkuhn> > > -- >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>>>>> Check the FAQ: http://akka.io/faq/ >>>>>>>>>> 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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