Thanks Endre On Fri, Jan 9, 2015 at 5:36 PM, Endre Varga <[email protected]> wrote:
> Hi Matan, > > On Fri, Jan 9, 2015 at 4:30 PM, Matan Safriel <[email protected]> wrote: > >> Thanks, good to know! Does it include a leader election process for when >> the leader isn't available? >> > > From the docs: > > "After gossip convergence a leader for the cluster can be determined. > There is no leader election process, the leader can always be recognised > deterministically by any node whenever there is gossip convergence. The > leader is just a role, any node can be the leader and it can change between > convergence rounds. The leader is simply the first node in sorted order > that is able to take the leadership role, where the preferred member states > for a leader are upand leaving (see the Membership Lifecycle section below > for more information about member states)." > > There is no explicit leader election because the leader can be always > implicitly determinable from the cluster CRDT state. > > >> I was not sure from the documentation whether the leader is a single >> point of failure, or its relationship to seed nodes. >> > > Leader is not a single point of failure, it changes many times during the > life of a cluster. > > Seed nodes are not special either, they are just a set of known IP > addresses to bootstrap from (i.e. a set of nodes that can be used to enter > the cluster, only one of them that is needed to be up at any time) when a > node wants to join. This idea is not unique to Akka, for example quoting > from the Cassandra docs: > > "Cassandra nodes exchange information about one another using a mechanism > called Gossip, but to get the ball rolling a newly started node needs to > know of at least one other, this is called a Seed. It's customary to pick a > small number of relatively stable nodes to serve as your seeds, but there > is no hard-and-fast rule here. Do make sure that each seed also knows of at > least one other, remember, the goal is to avoid a chicken-and-egg scenario > and provide an avenue for all nodes in the cluster to discover one another." > > -Endre > > > >> >> Maybe this should be a different thread. >> >> On Fri, Jan 9, 2015 at 5:15 PM, Endre Varga <[email protected]> >> wrote: >> >>> Hi, >>> >>> On Fri, Jan 9, 2015 at 4:12 PM, Matan Safriel <[email protected]> >>> wrote: >>> >>>> Thanks Patrik, good to know, because the cluster module may seem like a >>>> very specific and rather unfinished reference implementation; >>>> >>> >>> What do you mean by unfinished reference implementation? It is a fully >>> supported module of Akka. >>> >>> -Endre >>> >>> >>>> Good to have this in the core without relying on the cluster module. >>>> >>>> On Friday, January 9, 2015 at 11:25:30 AM UTC+2, Patrik Nordwall wrote: >>>>> >>>>> >>>>> >>>>> On Thu, Jan 8, 2015 at 9:56 PM, Matan Safriel <[email protected]> >>>>> wrote: >>>>> >>>>>> Sorry for awakening this old thread... >>>>>> Is it really the case that there is all this fancy supervision >>>>>> architecture, and then a remote actor that has gone non-responsive, needs >>>>>> to be handled outside of the supervision hierarchy alltogether? was it >>>>>> considered enabling supervision to work such that the supervisor would >>>>>> know >>>>>> in case its remote child has gone unresponsive/gated/quarantined? >>>>>> >>>>> >>>>> The information in this thread is outdated. We have added support for >>>>> proper remote death watch also when using remoting only (without cluster). >>>>> >>>>> >>>>>> >>>>>> Perhaps I misinterpret the reference to the "cluster module" in the >>>>>> response by Dr. Roland Kuhn below. >>>>>> >>>>>> Thanks for clarifying, >>>>>> Matan >>>>>> >>>>>> On Thursday, January 31, 2013 at 10:13:26 PM UTC+2, rkuhn wrote: >>>>>>> >>>>>>> Hi Juan Pablo, >>>>>>> >>>>>>> 30 jan 2013 kl. 22:08 skrev Juan Pablo Vergara Villarraga: >>>>>>> >>>>>>> If a remote actor is not available due to power loss Can the >>>>>>> supervision strategy handle the situation? >>>>>>> >>>>>>> >>>>>>> No, loss of actors is managed by the Death Watch ( >>>>>>> http://doc.akka.io/docs/akka/2.1.0/general/supervision.html >>>>>>> #What_Lifecycle_Monitoring_Means >>>>>>> <http://www.google.com/url?q=http%3A%2F%2Fdoc.akka.io%2Fdocs%2Fakka%2F2.1.0%2Fgeneral%2Fsupervision.html%23What_Lifecycle_Monitoring_Means&sa=D&sntz=1&usg=AFQjCNFsY9OHlk2bVT8CIYRVEBaNRchLyA>), >>>>>>> but support for detecting unreachable remote nodes is only present in >>>>>>> the >>>>>>> cluster module. >>>>>>> >>>>>>> I have coded the example and I have shut down the remote actor >>>>>>> system but it seems that the supervision strategy only takes into >>>>>>> account >>>>>>> Exceptions thrown by the remote actor once reached. >>>>>>> >>>>>>> >>>>>>> Yes, that is correct. >>>>>>> >>>>>>> I have already implemented the subscription to the events that >>>>>>> indicates that error in the connection have occurred. I still need to >>>>>>> have >>>>>>> access to message the sender sent originally so the message do not get >>>>>>> lost. >>>>>>> >>>>>>> >>>>>>> There is nothing you can subscribe to which tells you whether a >>>>>>> given message was processed on the remote system. If you cannot lose >>>>>>> messages then you need to persist them and use explicit acknowledgements >>>>>>> from the receiving actor to retire them from the local storage. You will >>>>>>> also need to implement resending and deduplication if you need >>>>>>> exactly-once >>>>>>> delivery; you might want to read the documentation on message delivery >>>>>>> guarantees: http://doc.akka.io/docs/akka/2.1.0/general/messa >>>>>>> ge-delivery-guarantees.html >>>>>>> >>>>>>> Regards, >>>>>>> >>>>>>> Roland >>>>>>> >>>>>>> JP. >>>>>>> >>>>>>> -- >>>>>>> >>>>>>>>>> Read the docs: http://akka.io/docs/ >>>>>>> >>>>>>>>>> Check the FAQ: http://akka.io/faq/ >>>>>>> >>>>>>>>>> Search the archives: https://groups.google.com/grou >>>>>>> p/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?hl=en. >>>>>>> For more options, visit https://groups.google.com/groups/opt_out. >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> *Dr. Roland Kuhn* >>>>>>> *Akka Tech Lead* >>>>>>> Typesafe <http://typesafe.com/> – Empowering professional >>>>>>> developers to build amazing apps. >>>>>>> twitter: @rolandkuhn <http://twitter.com/#!/rolandkuhn> >>>>>>> >>>>>>> -- >>>>>> >>>>>>>>>> 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 [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/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 [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/d/optout. >>>> >>> >>> -- >>> >>>>>>>>>> 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 a topic in the >>> Google Groups "Akka User List" group. >>> To unsubscribe from this topic, visit >>> https://groups.google.com/d/topic/akka-user/68TuTZLxqFI/unsubscribe. >>> To unsubscribe from this group and all its topics, 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/d/optout. >>> >> >> -- >> >>>>>>>>>> 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 [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/d/optout. >> > > -- > >>>>>>>>>> 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 a topic in the > Google Groups "Akka User List" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/akka-user/68TuTZLxqFI/unsubscribe. > To unsubscribe from this group and all its topics, 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/d/optout. > -- >>>>>>>>>> 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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