Shutdown

[Maatary Okouya]

Hi, 

I wonder what is happening behind the scene is spray .....

Why do we have to call actor shutdown for the application to actually terminate here. 

What i mean is that, usually in the main thread of my akka appliation. I will have an awaitTermination. If i don't have this there is no need to call a shutdown anyway, because the main will end and the program with it. 

I have tested and commented the shutdown method and indeed it does not terminate. 

Please could you explain ?

object Main extends App {
  // we need an ActorSystem to host our application in
  implicit val system = ActorSystem("simple-spray-client")
  import system.dispatcher // execution context for futures below
  val log = Logging(system, getClass)

  log.info("Requesting the elevation of Mt. Everest from Googles Elevation API...")

  import ElevationJsonProtocol._
  import SprayJsonSupport._
  val pipeline = sendReceive ~> unmarshal[GoogleApiResult[Elevation]]

  val responseFuture = pipeline {
    Get("http://maps.googleapis.com/maps/api/elevation/json?locations=27.988056,86.925278&sensor=false")
  }
  responseFuture onComplete {
    case Success(GoogleApiResult(_, Elevation(_, elevation) :: _)) =>
      log.info("The elevation of Mt. Everest is: {} m", elevation)
      shutdown()

    case Success(somethingUnexpected) =>
      log.warning("The Google API call was successful but returned something unexpected: '{}'.", somethingUnexpected)
      shutdown()

    case Failure(error) =>
      log.error(error, "Couldn't get elevation")
      shutdown()
  }

  def shutdown(): Unit = {
    IO(Http).ask(Http.CloseAll)(1.second).await
    system.shutdown()
  }
}

[Patrik Nordwall]

On Wed, Feb 11, 2015 at 9:35 PM, Maatary Okouya <maatar...@gmail.com> wrote:

Hi, 

I wonder what is happening behind the scene is spray .....

Why do we have to call actor shutdown for the application to actually terminate here. 

What i mean is that, usually in the main thread of my akka appliation. I will have an awaitTermination. If i don't have this there is no need to call a shutdown anyway, because the main will end and the program with it. 

Akka threads are by default not daemonic, which means that a started ActorSystem will keep the JVM alive until you shutdown the ActorSystem. You don't need to awaitTermination in a separate thread.

/Patrik

 

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Patrik Nordwall
Typesafe -  Reactive apps on the JVM
Twitter: @patriknw

[Maatary Okouya]

Got it thanks

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