I noticed one subtle thing in my cassandra entity persistence.
In my Subscriber class.
If I use the "ActorRef myEntity =
ClusterSharding.get(getContext().system()).shardRegion("MyEntity");" then I
see the persistence_id='counter-worker-MyEntity123'.
Where as, if I use the previously mentioned approach which is ( ActorRef
myEntity = getContext().actorOf(Props.create(MyEntity.class), "myEntity");)
then i see the persistence_id='counter-worker-myEntity'.
The above observation tells me that forwarding via Supervisor actor
instance is not invoking ShardRegion.MessageExtractor 'entityId' overrider
which is required for my MyEntity.class
@Override
public String persistenceId() {
return "counter-worker-" + getSelf().path().name();
}
In my subscriber startup class i am starting the Subscriber sharding the
following way.
ClusterSharding.get(system).start("Subscriber",
Props.create(Subscriber.class), settings, messageExtractor);
Not sure, what else is needed. That actually makes think is it supported at
all? But the documentation says otherwise.
Please review my code at the following link.
https://github.com/sdab75/akka-cluster-sharding-example/tree/master
I spent several days debugging this issue. Any help appreciated.
Thanks,
SD
On Monday, November 9, 2015 at 1:33:35 PM UTC-5, sd d wrote:
>
> *Source code github link:*
>
>
> https://github.com/sdab75/akka-cluster-sharding-example/tree/master
>
>
> I am struggling to get the persistent actor and akka cluster sharding
> “supervisor” combination work.
>
>
> The cluster sharding ‘without’ akka supervisor works fine i.e. in my
> Subscriber if I get the sharded region entity via “ActorRef myEntity =
> ClusterSharding.get(getContext().system()).shardRegion("MyEntity");” and
> use the myEntity reference to forward the received messages to my
> persistent actor entity “MyEntity.class”.
>
>
> However, this approach doesn’t fire the parent (‘Subscriber’ actor)
> supervisor strategy.
>
>
> According to the Akka documentation (
> http://doc.akka.io/docs/akka/2.4.0/java/cluster-sharding.html). I am
> supposed to forward received message via parent actor “ActorRef myEntity =
> getContext().actorOf(Props.create(MyEntity.class), "myEntity");”. This
> works as long as I have ‘one Subscriber node’ in the cluster (i.e. on
> exception, parent actor supervisor strategy gets invoked), the minute we
> add an additional ‘Subscriber’ node the persistence goes havoc and does
> only partial persistence i.e. if I publish 10 messages I only 6 or 7
> messages getting persisted.
>
>
> I have checked in the code in my git hub. Please let me know if If the
> cluster sharding supervisor is fully tested in akka distribute pub/sub
> scenario for akka 2.4.0.I followed the documentation from this URL (
> http://doc.akka.io/docs/akka/2.4.0/java/cluster-sharding.html).
>
>
> *Example setup*
>
> 1. The PubCluster publishes a topic named ‘content’ that has myCounter
> instance. Currently PubClusterApp uses pub actor with round robbin pool of
> 5 ( ‘ActorRef pub =
> system.actorOf(Props.create(Publisher.class).withRouter(new
> RoundRobinPool(5)), "publisher");’.).
> 2. There are 2 subscriber apps (SubClusterApp1, SubClusterApp2)both
> uses the same Subscriber uses the same group ‘grp1’.
>
> *Sucessful scenario with one ‘Subscriber’ node in the cluster.*
>
> 1. Start SubClusterApp1 (akka 2550)
> 2. Start PubClusterApp (akka 2552)
>
> This will perfectly save all the messages and and also notifies the
> supervisor on the exception.
>
> *Failure scenario*
>
> when I start 2 subcriber nodes I see both nodes recieveing messages but
> only few messages are getting saved.
>
> 1. Start SubClusterApp1 (akka 2550)
> 2. Start SubClusterApp1 (akka 2551)
> 3. Start PubClusterApp (akka 2552)
>
> If the cluster sharding based fault tolerance doesn’t work in a multi node
> scenarios then I am not sure how far we can use akka for production
> scenarios. Any help in clarifying the issue appreciated.
>
>
> Thanks,
>
> SD
>
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