这是 Scala 2.9.0.1 演员库中的错误吗 [英] Is this a bug in scala 2.9.0.1 actor library

问题描述

以下代码在 Scala 2.8 中工作正常，但在 2.9.0.1 中无效(复制并粘贴到 REPL 中).这将在 2.9.0.1 中抛出异常.

The following code works fine in Scala 2.8 but not in 2.9.0.1 (copy and paste in REPL). This will throw an exception in 2.9.0.1.

import scala.actors.Actor
import scala.actors.TIMEOUT

object A2 extends Actor {
  def act = {
    loop {
      react {
        case "hello" => 
          val s = sender 
          reactWithin(2000){
            case i:Int => s ! "hello"
            case TIMEOUT => s ! "TIMEOUT"
          }
        case _ => 
      }
    }
  }
}

object A1 extends Actor {
  def act = {
    loop {
      react {
        case m:String => println (A2 !? (1000, m))
        case _ =>
      }
    }
  }
}

A1.start
A2.start

A1 ! "hi"
A1 ! "hello"

如果没有立即抛出异常，继续执行 A1 ！嗨" 或 A1 ！你好"几次.

If the exception is not thrown immediately, keep doing A1 ! "hi" or A1 ! "hello" a few times.

这是 Scala 2.9.0.1 中的错误，还是代码有问题?

Is this a bug in Scala 2.9.0.1, or something wrong with the code?

忘记添加实际抛出的异常.

Forgot to add the actual exception thrown.

scala> $line4.$read$$iw$$iw$A1$@6be03fce: caught java.lang.RuntimeException: unhandled timeout
java.lang.RuntimeException: unhandled timeout
    at scala.sys.package$.error(package.scala:27)
    at scala.actors.Actor$class.receiveWithin(Actor.scala:606)
    at $line4.$read$$iw$$iw$A1$.receiveWithin(<console>:10)
    at scala.actors.Channel.receiveWithin(Channel.scala:71)
    at scala.actors.ActorCanReply$class.$bang$qmark(ActorCanReply.scala:32)
    at $line3.$read$$iw$$iw$A2$.$bang$qmark(<console>:9)
    at $line4.$read$$iw$$iw$A1$$anonfun$act$1$$anonfun$apply$1.apply(<console>:15)
    at $line4.$read$$iw$$iw$A1$$anonfun$act$1$$anonfun$apply$1.apply(<console>:13)
    at scala.actors.ReactorTask.run(ReactorTask.scala:31)
    at scala.actors.Reactor$class.resumeReceiver(Reactor.scala:129)
    at $line4.$read$$iw$$iw$A1$.scala$actors$ReplyReactor$$super$resumeReceiver(<console>:10)
    at scala.actors.ReplyReactor$class.resumeReceiver(ReplyReactor.scala:68)
    at $line4.$read$$iw$$iw$A1$.resumeReceiver(<console>:10)
    at scala.actors.Actor$class.searchMailbox(Actor.scala:500)
    at $line4.$read$$iw$$iw$A1$.searchMailbox(<console>:10)
    at scala.actors.Reactor$$anonfun$startSearch$1$$anonfun$apply$mcV$sp$1.apply$mcV$sp(Reactor.scala:117)
    at scala.actors.Reactor$$anonfun$startSearch$1$$anonfun$apply$mcV$sp$1.apply(Reactor.scala:114)
    at scala.actors.Reactor$$anonfun$startSearch$1$$anonfun$apply$mcV$sp$1.apply(Reactor.scala:114)
    at scala.actors.ReactorTask.run(ReactorTask.scala:33)
    at scala.concurrent.forkjoin.ForkJoinPool$AdaptedRunnable.exec(ForkJoinPool.java:611)
    at scala.concurrent.forkjoin.ForkJoinTask.quietlyExec(ForkJoinTask.java:422)
    at scala.concurrent.forkjoin.ForkJoinWorkerThread.mainLoop(ForkJoinWorkerThread.java:340)
    at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:325)

没有 REPL 的独立程序

Standalone program without REPL

package scalaapplication5
import scala.actors.Actor._
import scala.actors.Actor
import scala.actors.TIMEOUT


object Main {
  A1.start
  A2.start
  def main(args: Array[String]): Unit = {
    while (true){
      A1 ! "hi"
      A1 ! "hello"
      Thread.sleep(1000)
    }
  }
}

object A2 extends Actor {
  def act = loop { 
    react {
      case "hello" =>
        val s = sender
        reactWithin(2000){
          case i:Int => s ! "hello"
          case TIMEOUT => s ! "TIMEOUT"
        }
      case _ =>
    }
  }
}

object A1 extends Actor {
  def act = {
    loop {
      react {
        case m:String => println (A2 !? (1000, m))
        case _ =>
      }
    }
  }
}

推荐答案

这似乎是 Actor 框架中的一个错误.看起来您永远不应该得到 RuntimeException.有关详细信息，请参阅 Scala 错误跟踪器.它已于 2011 年 7 月 7 日修复，可能正在等待发布.

This does appear to have been a bug in the Actor framework. Looks like you're never supposed to get a RuntimeException. See the Scala Bug Tracker for details. It was fixed July 7th 2011, and is probably awaiting release.

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