Akka Scheduler仅在MicroKernel中引发异常，但在Eclipse IDE for scala中可以正常工作 [英] Akka Scheduler throws exceptions only in MicroKernel but works fine in eclipse IDE for scala

问题描述

我有一个如下所示的调度程序。它的目的是每30分钟将消息发送给Actor系统中的另一个actor。当我在用于scala的eclipse IDE中运行该代码时，它运行良好。
但是，当我在MicroKernel中将此代码（与可引导程序一起使用，以便Microkernel可以调用它）时，出现异常，提示

I have a scheduler that looks like given below. It is meant to send a message every 30 minute to another actor in the Actor system. This code works fine when I run it in eclipse IDE for scala. However when I throw this code(with the bootable so that Microkernel can invoke it) in MicroKernel, I get an exception saying

java.lang.NoSuchMethodError： akka.actor.ActorSystem.dispatcher（）Lscala / concurrent / ExecutionContext;
完整的堆栈跟踪如下所示。
我怀疑问题可能与在这种情况下无效的 import system.dispatcher行有关。或调度程序试图过早地发送消息。

java.lang.NoSuchMethodError: akka.actor.ActorSystem.dispatcher()Lscala/concurrent/ExecutionContext; The full stack trace is given below. I suspect the problem might be related to "import system.dispatcher" line that is not valid in this context. Or the Scheduler is trying to fire the message too soon.

请帮助...

scheduler.scala：

import akka.actor.Actor
import akka.actor.Props
import scala.concurrent.duration._
import akka.actor._
import java.sql.Timestamp;
import java.util.Date;

class Scheduler extends Actor with ActorLogging {
    import transactions._

    val system = ActorSystem("Daemon")
    import system.dispatcher
    log.info("Scheduler initializing.")
    system.scheduler.schedule( 30 milliseconds, (1000*60*30 ) milliseconds){ 
                self! updateUows(new Timestamp(new java.util.Date().getTime()))}

    def receive = {

    case updateUows(time) => { 
        log.info("updateuow to be sent.")
        context.parent!updateUows(time) 
    }
    }

}

完整堆栈跟踪：

    [DEBUG] [07/26/2013 15:38:23.324] [Daemon-akka.actor.default-dispatcher-4] [EventStream(akka://Daemon)] Default Loggers started
Uncaught error from thread [Daemon-akka.actor.default-dispatcher-4] shutting down JVM since 'akka.jvm-exit-on-fatal-error' is enabled for ActorSystem[Daemon[ERROR] [07/26/2013
15:38:23.960] [Daemon-akka.actor.default-dispatcher-4] [ActorSystem(Daemon)] Uncaught error from thread [Daemon-akka.actor.default-dispatcher-4] shutting down JVM since 'akka
.jvm-exit-on-fatal-error' is enabled
java.lang.NoSuchMethodError: akka.actor.ActorSystem.dispatcher()Lscala/concurrent/ExecutionContext;
        at org.exactearth.PVDaemon.Scheduler$$anonfun$receive$1.applyOrElse(Scheduler.scala:25)
        at akka.actor.ActorCell.receiveMessage(ActorCell.scala:425)
        at akka.actor.ActorCell.invoke(ActorCell.scala:386)
        at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:230)
        at akka.dispatch.Mailbox.run(Mailbox.scala:212)
        at akka.dispatch.ForkJoinExecutorConfigurator$MailboxExecutionTask.exec(AbstractDispatcher.scala:506)
        at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
        at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
        at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
        at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
]

java.lang.NoSuchMethodError: akka.actor.ActorSystem.dispatcher()Lscala/concurrent/ExecutionContext;
        at org.exactearth.PVDaemon.Scheduler$$anonfun$receive$1.applyOrElse(Scheduler.scala:25)
        at akka.actor.ActorCell.receiveMessage(ActorCell.scala:425)
        at akka.actor.ActorCell.invoke(ActorCell.scala:386)
        at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:230)
        at akka.dispatch.Mailbox.run(Mailbox.scala:212)
        at akka.dispatch.ForkJoinExecutorConfigurator$MailboxExecutionTask.exec(AbstractDispatcher.scala:506)
        at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
        at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
        at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
        at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)

Shutting down Akka...
Shutting down .............(my program)

推荐答案

应该使用下面的代码使用ActorSystem创建Actors：

It should create Actors with ActorSystem like in the code below:

case object StartSched

class Test extends Actor with ActorLogging {
  def receive = {
    case StartSched =>
      context.system.scheduler.schedule( 30 milliseconds, (1000*60*30) milliseconds){
        self ! updateUows(new Timestamp(new java.util.Date().getTime()))
      }
  }
}

object Main {
  def main(args: Array[String]) {
    val sys = ActorSystem("Test")
    sys.actorOf(Props[Test])
  }
}

要在MicroKernel中启动它，您应该扩展 Bootable 特性和重载两种方法：启动和关闭。 文档

To start it in MicroKernel you should extend Bootable trait and overload two methods: startup and shutdown. Docs

在Actor中创建ActorSystem 是一个非常糟糕的决定。

And creating ActorSystem inside an Actor is a very bad decision.

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