El siguiente código arroja unjava.lang.IllegalMonitorStateException excepción cuando apago el servidor de juego; es causado por ela. espera (1000) llamar alonStop método. ¿Alguien podría decirme por qué este es el caso y cómo esperar con gracia a que un actor complete el cierre del marco de Play?

import play.api.GlobalSettings
import play.api.libs.concurrent.Akka
import akka.actor.{ Actor, Props }
import play.api.libs.concurrent.Execution.Implicits.defaultContext
import play.api.Play.current
import models.{ TestActor, StartMessage, StopMessage }

object Global extends GlobalSettings {

    override def onStart(application : play.api.Application) {
        val a = Akka.system.actorOf(Props[TestActor], name = "test-actor")
        a ! StartMessage("Start instruction")

    }

    override def onStop(application : play.api.Application) {
        val a = Akka.system.actorSelection("akka://application/user/test-actor")
        a ! StopMessage("Stop instruction")
        a.wait(1000)
        Akka.system.shutdown()
    }
}

Actualizar:

Aquí está la solución completa, teniendo la siguiente respuesta:

import play.api.GlobalSettings
import play.api.libs.concurrent.Akka
import akka.actor.{ Actor, Props }
import play.api.libs.concurrent.Execution.Implicits.defaultContext
import play.api.Play.current
import models.{ TestActor, StartMessage, StopMessage }
import akka.pattern.gracefulStop
import scala.concurrent.Future
import scala.concurrent.duration.FiniteDuration
import scala.concurrent.Await
import com.typesafe.config.impl.ResolveContext
import com.typesafe.config.impl.ResolveContext
import akka.actor.ActorIdentity

object Global extends GlobalSettings {

    override def onStart(application : play.api.Application) {
        val a = Akka.system.actorOf(Props[TestActor], name = "test-actor")
        a ! StartMessage("Start Instruction")
    }

    override def onStop(application : play.api.Application) {
        val a = Akka.system.actorFor("akka://application/user/test-actor")
        a ! StopMessage("Stop Instruction")

        try {
            val stopped : Future[Boolean] = gracefulStop(a, scala.concurrent.duration.Duration(5, "seconds"))
            Await.result(stopped, scala.concurrent.duration.Duration(6, "seconds"))
            // the actor has been stopped
        }
        catch {
            case e : akka.pattern.AskTimeoutException => // the actor wasn't stopped within 5 seconds
        }

        Akka.system.shutdown()
        Akka.system.awaitTermination()
    }
}