Hello Friends,
I need your help in figuring out what is going wrong here. I have posted
this question in SO too.
I am using Akka Cluster (version 2.4.10) with few nodes designated for
"front-end" role and few others as "workers". The workers are on remote
machines. The incoming work is distributed by the front-end actor to
workers by round-robin routing. The issue is sending back the response from
the "workers" back to the front-end actor. I can see that the work is
getting completed by the workers. But the message sent back by the workers
to front-end does not reach and ends up as dead-letters. I see the below
error in the log.
[Cluster-akka.actor.default-dispatcher-21] [akka://Cluster/deadLetters]
Message [scala.collection.immutable.$colon$colon] from
Actor[akka://Cluster/user] to Actor[akka://Cluster/deadLetters] was not
delivered. [6] dead letters encountered.
The round-robin router configuration is as below.
akka.actor.deployment {
/frontEnd/hm = {
router = round-robin-group
nr-of-instances = 5
routees.paths = ["/user/hmWorker"]
cluster {
enabled = on
use-role = backend
allow-local-routees = on
}
}
}
The router is instantiated in front-end actor like below.
val router = context.actorOf(FromConfig.props(), name = "hm")
val controller = context.actorOf(Props(classOf[Controller], router))
The controller and the worker codes are below.
// Node 1 : Controller routes requests using round-robin
class Controller(router: ActorRef) extends Actor {
val list = List("a", "b") // Assume this is a big list
val groups = list.grouped(500)
override def receive: Actor.Receive = {
val futures = groups.map(grp => (router ?
Message(grp)).mapTo[List[String]]))
val future = Future.sequence(futures).map(_.flatten)
val result = Await.result(future, 50 seconds)
println(s"Result is $result")
}
}
// Node 2
class Worker extends Actor {
override def receive: Actor.Receive = {
case Message(lst) =>
val future: Future[List[String]] = // Do Something asynchronous
future onComplete {
case Success(r) => sender.!(r)(context.parent) // This message is not
delivered to Controller actor.
case Failure(th) => // Some error handling
}
}
}
Appreciate your help.
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