Akka期货例外 [英] Akka Futures Exceptions

问题描述

根据 http://doc.akka.io/docs/akka/snapshot/scala/futures.html ：

如果一个Actor或调度程序正在完成
，那么没有关系未来，如果一个异常被捕获，Future将包含它，而不是
的有效结果。如果未来确实包含异常，调用
Await.result将导致它再次抛出，以便它可以正确处理
。

我不知道这是我运行这段代码时看到的：

  class Worker扩展Actor {
 def receive = {
 case i：Int =>抛出新的RuntimeException 
} 
} 
 
隐式val系统= ActorSystem（MySystem）
 val worker = system.actorOf（Props（new Worker），name = worker）
 implicit val timeout =超时（5分钟）
 val future = worker？ 0 
 val res = Await.result（未来，10秒）
  

根据文档Await.result应该再次抛出异常，但是我得到的是一个TimeoutException！有人可以澄清这一点吗？

解决方案

对于演员，你需要捕获异常和将其作为失败状态返回。现在你没有给发件人返回任何东西，所以你得到一个超时异常：

  class Worker extends Actor {
 def receive = {
 case i：Int => {
 try {
 throw new RuntimeException 
 sender！ 一些好的结果
} catch {
 case e：Exception => 
发件人！ akka.actor.Status.Failure（e）//提醒失败的发件人
 throw e //提醒任何失败的主管演员
} 
} 
} 
} 
  

期货可以更好地处理这一点，因为他们总是发送结果，而演员不（这会给你以上一样的结果）：

  val future = Future {
 throw new RuntimeException 
} 
  

What happens when an actor of a future throws an exception?

According to the Akka documentation at http://doc.akka.io/docs/akka/snapshot/scala/futures.html:

It doesn't matter if an Actor or the dispatcher is completing the Future, if an Exception is caught the Future will contain it instead of a valid result. If a Future does contain an Exception, calling Await.result will cause it to be thrown again so it can be handled properly.

I am not sure this is what I am seeing when running this piece of code:

  class Worker extends Actor {
    def receive = {
      case i: Int => throw new RuntimeException
    }         
  }

  implicit val system = ActorSystem("MySystem")
  val worker = system.actorOf(Props(new Worker), name="worker")
  implicit val timeout = Timeout(5 minutes)
  val future = worker ? 0
  val res = Await.result(future, 10 seconds)

According to the documentation, Await.result should throw the exception again, but what I am getting is a TimeoutException! Can someone clarify on this?

解决方案

For actors you need to catch the exception and return it as a failure status. Right now you're not returning anything to the sender so you're getting a timeout exception:

class Worker extends Actor {
  def receive = {
    case i: Int => {
      try {
        throw new RuntimeException
        sender ! "Some good result"
      } catch {
        case e: Exception =>
          sender ! akka.actor.Status.Failure(e) // Alert the sender of the failure
          throw e // Alert any supervisor actor of the failure
      }
    }
  }
}

Futures can handle this a little more gracefully since they always send a result, while actors do not (this would give you the same result as above):

  val future = Future {
    throw new RuntimeException
  }

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