Re: [akka-user] How catch exception raise in the preStart method for top level actor

[Roland Kuhn]

Hi Paolo,

relying on the guardian to get things right is not recommended for real applications: typically your application will have several components which when failing require the application to stop or respond in some very specific manner. Hence my recommendation would be to just create a single top-level actor for one application, which will then create the “top-level” services as its children. This allows you to have full control over all failure scenarios and also enables you to cleanly shutdown the system if this application guardian detects a fatal error condition.

Now to your question: if you don’t put any code in preStart, then it will also not fail. The application guardian could look like this:

class MyApp extends Actor {

  override val supervisorStrategy = …

  def receive = {

    case START =>

      context.actorOf(Props[ServiceA], "serviceA")

      …

  }

  // or set StoppingStrategy for the guardian (see akka.actor.guardian-supervisor-strategy)

  override def preRestart(...) { context.system.shutdown(); context.stop(self) }

}

and then have a main() which does:

val sys = ActorSystem(…)

sys.actorOf(Props[MyApp], "app") ! START

If anything goes wrong within the MyApp actor, the system will be shut down (or you can do whatever is appropriate).

Regards,

Roland

7 feb 2013 kl. 13:57 skrev Paolo Di Tommaso:

Dear all, 

I'm wondering how to catch an exception raised in the preStart for a top-level actor. 

As far I've understood for children actors I can override the default SupervisorStrategy to handle it. But how to manage it for the top most actor ? 

Cheers,

Paolo

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Dr. Roland Kuhn
Akka Tech Lead
Typesafe – Empowering professional developers to build amazing apps.
twitter: @rolandkuhn