Hi Dennis, On Fri, Sep 12, 2014 at 9:57 PM, Dennis Vriend <[email protected]> wrote:
> Hi, > > akka-persistence-testkit has no test for this case, it's an Akka cluster > issue as far as I can tell. Most use cases create snapshots based upon some > kind of counter variable every 100 of journal entries (persist calls) or > so, to create snapshot instances, thus changing the internal state, but > when the state does not change, the snapshot counter stays the same. One > could however change the state, and write snapshots explicitly, skipping > the persist call to write journal entries, but somehow this does not feel > correct. I agree, the cluster sharding is using the wrong approach and that will be corrected <https://github.com/akka/akka/issues/15619>. However, a snapshot journal must be handle this scenario, since we can't enforce that the user is not calling saveSnapshot several times for the same sequence number. I have created an issue <https://github.com/akka/akka/issues/15889> to add this to the Persistence TCK. > To make the cluster use case work, the jdbc plugin updates the snapshot > entry from v1.0.6 on, and this works, Thanks Cheers, Patrik > but again, this does not feel correct to me. The base concept of > event-sourcing is the journal, a change in state must be reflected in the > journal, and bypassing it feels wrong. > > On a side note I would advice using Apache Cassandra and the > akka-persistence-cassandra plugin for cluster solutions so that the storage > backend has the same trait as akka-cluster, both distributed and scalable. > The jdbc plugin uses a blocking driver, and it would be easy to overload > the default-dispatcher when the load is very high on the node's Actor > system. Beware that Akka is no Application Server and it is tuned for > non-blocking operations only and the tuning of the default-dispatcher > reflects this fact. Akka is like a highly tuned Japanese sports car, and > the AppServer is like a 1960's muscle car, both have their uses... > > Cheers, > > Dennis > > -- > >>>>>>>>>> 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.
