Demonstrates changing the default Stop supervision behaviour on a top level actor encountering an exception/error during initialization (above /user guardian actor). Demonstrates how exceptions are thrown out of akka extensions as well (they throw like any other class).

gistfile1.scala

import akka.actor._
import akka.actor.SupervisorStrategy._
import akka.routing.RoundRobinRouter

object Main {
  val system = ActorSystem("TestActorSystem")

  val escalator = OneForOneStrategy() {
    case e: ActorInitializationException ⇒
      println("Got exception during actor start: " + e)
      throw new Error
      Stop
  }

  val router = system.actorOf(Props[TestActor].withRouter(
    RoundRobinRouter(1, supervisorStrategy = escalator)))

  def main(args: Array[String]) {
    router ! "HelloWorld"
  }
}

class TestActor extends Actor {
  override def preStart {
    TestExtension(context.system) //Throws an error. Gets wrapped in ActorInitializationException. Causes actor stop.
  }

  def receive = {
    case msg ⇒ println(msg)
  }
}

class TestExtensionImpl extends Extension {
  throw new Error("This is the error")
}

object TestExtension
    extends ExtensionId[TestExtensionImpl]
    with ExtensionIdProvider {

  override def lookup = TestExtension
  override def createExtension(system: ExtendedActorSystem) = new TestExtensionImpl
}