[akka-user] ask returns nothing when tell is used in future

[Gabi Nir]

The following code uses 2 asks and initially seems like it supposed to 
print *"This should be printed in actor1 but most of the time wont because 
of a race condition with the receive method finishing"*. However there 
seems to be a race condition between the 'receive' method finishing and the 
future finishing and thus nothing is printed. Is this the intended behavior 
by akka? is this a bug? I am trying to avoid using 'ask' as much as 
possible and using 'tell' instead, but sometimes it's a must.

Also posted this on stackoverflow but figured here I'll get a better answer.
http://stackoverflow.com/questions/31387842/akka-ask-returns-nothing-when-tell-is-used-in-future

import akka.actor._
import akka.routing.SmallestMailboxPool
import akka.util.Timeout
import akka.pattern.ask
import scala.concurrent.duration._
import scala.concurrent.ExecutionContext.Implicits.global
import scala.util.{Failure, Success}

object ActorsAskingStuff extends App {
  val system = ActorSystem("abc-system")
  val actor1 = system.actorOf(Props[Actor1].withRouter(SmallestMailboxPool(1)), 
"actor1")
  actor1 ! 5
}

class Actor1 extends Actor {
  implicit val timeout = Timeout(60 seconds)
  val actor2: ActorRef = 
context.actorOf(Props[Actor2].withRouter(SmallestMailboxPool(1)), "actor2")
  override def receive: Receive = {
    case _ =>
      println("actor1 was called")
      actor2 ? "hello" onComplete {
      case Success(a) => println(a)
      case Failure(b) => println("FAILURE")
    }
  }
}

class Actor2 extends Actor {
  implicit val timeout = Timeout(6 seconds)
  val actor3: ActorRef = 
context.actorOf(Props[Actor3].withRouter(SmallestMailboxPool(1)), "actor3")
  override def receive: Actor.Receive = {
    case _ =>
      println("actor2 was called")
      actor3 ? "hello" map {
        _ =>
          println("Actor2 completed the future")
          sender ! "This should be printed in actor1 but most of the time wont 
because of a race condition with the receive method finishing"
      }

      // uncomment this to make it work
      //Thread.sleep(100)
  }
}

class Actor3 extends Actor {
  override def receive: Actor.Receive = {
    case _ =>
      println("actor3 was called")
      sender ! "I'm actor3"
  }
}



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