我试图在akka Actors中获得容错行为。我正在研究一些代码，这些代码依赖于系统中的Actors可用于长时间的处理。我发现我的处理在几个小时后停止（它应该需要大约10个小时）并且没有太多事情发生。我相信我的演员没有从异常中恢复过来。
我需要做什么才能永久地重新启动Actors一对一的基础？我希望可以通过此文档http://akka.io/docs/akka/1.1.3/scala/fault-tolerance
完成此操作我正在使用akka 1.1.3和scala 2.9
import akka.actor.Actor
import akka.actor.Actor._
import akka.actor.ActorRef
import akka.actor.MaximumNumberOfRestartsWithinTimeRangeReached
import akka.dispatch.Dispatchers
import akka.routing.CyclicIterator
import akka.routing.LoadBalancer
import akka.config.Supervision._
object TestActor {
val dispatcher = Dispatchers.newExecutorBasedEventDrivenWorkStealingDispatcher("pool")
.setCorePoolSize(100)
.setMaxPoolSize(100)
.build
}
class TestActor(val name: Integer) extends Actor {
self.lifeCycle = Permanent
self.dispatcher = TestActor.dispatcher
def receive = {
case num: Integer => {
if( num % 2 == 0 )
throw new Exception("This is a simulated failure")
println("Actor: " + name + " Received: " + num)
//Thread.sleep(100)
}
}
override def postStop(){
println("TestActor post Stop ")
}
//callback method for restart handling
override def preRestart(reason: Throwable){
println("TestActor "+ name + " restaring after shutdown because of " + reason)
}
//callback method for restart handling
override def postRestart(reason: Throwable){
println("Restaring TestActor "+name+"after shutdown because of " + reason)
}
}
trait CyclicLoadBalancing extends LoadBalancer { this: Actor =>
val testActors: List[ActorRef]
val seq = new CyclicIterator[ActorRef](testActors)
}
trait TestActorManager extends Actor {
self.lifeCycle = Permanent
self.faultHandler = OneForOneStrategy(List(classOf[Exception]), 1000, 5000)
val testActors: List[ActorRef]
override def preStart = testActors foreach { self.startLink(_) }
override def postStop = { System.out.println("postStop") }
}
object FaultTest {
def main(args : Array[String]) : Unit = {
println("starting FaultTest.main()")
val numOfActors = 5
val supervisor = actorOf(
new TestActorManager with CyclicLoadBalancing {
val testActors = (0 until numOfActors toList) map (i => actorOf(new TestActor(i)));
}
)
supervisor.start();
println("Number of Actors: " + Actor.registry.actorsFor(classOf[TestActor]).length)
val testActor = Actor.registry.actorsFor(classOf[TestActor]).head
(1 until 200 toList) foreach { testActor ! _ }
}
}
此代码在LoadBalancer后面设置5个Actors，它们只打印发送给它们的整数，除了它们在偶数上抛出异常以模拟故障。整数0到200被发送到这些Actors。我希望奇数可以得到输出，但是在偶数偶数故障后，一切似乎都会关闭。使用sbt运行此代码会导致此输出：
[info] Running FaultTest
starting FaultTest.main()
Loading config [akka.conf] from the application classpath.
Number of Actors: 5
Actor: 2 Received: 1
Actor: 2 Received: 9
Actor: 1 Received: 3
Actor: 3 Received: 7
[info] == run ==
[success] Successful.
[info]
[info] Total time: 13 s, completed Aug 16, 2011 11:00:23 AM
我认为这里发生的是5名演员开始，前5名偶数让他们破产，他们没有重新开始。
如何更改此代码以便Actors从异常中恢复？
我希望这实际上会打印出从1到200的所有奇数。我认为每个参与者都会在偶数上失败，但会在例外情况下重新启动一个已插入的邮箱。我希望看到来自preRestart和postRestart的println。需要在此代码示例中配置哪些内容才能实现这些目标？
以下是关于akka和演员的一些额外假设，可能会导致我的误解。我假设可以使用Supervisor或faultHandler配置Actor，以便在接收期间抛出异常时重新启动并继续可用。我假设发送给actor的消息如果在接收期间抛出异常将丢失。我假设将调用抛出异常的actor上的preRestart（）和postRestart（）。
代码示例代表我正在尝试做的事情并基于Why is my Dispatching on Actors scaled down in Akka?
**另一个代码示例**
这是另一个更简单的代码示例。我正在启动一个在偶数上抛出异常的actor。在路上没有负载均衡器或其他东西。我正在尝试打印出有关演员的信息。在将消息发送给Actor并监视正在发生的事情之后，我等待退出程序一分钟。
我希望这会打印出奇数，但看起来Actor会在邮箱中找到消息。
我是否将OneForOneStrategy设置错误？我需要将Actor链接到某个东西吗？我的这种配置是否从根本上误导了我？ Dispatcher是否需要设置容错？我可以搞乱Dispatcher中的线程吗？
import akka.actor.Actor
import akka.actor.Actor._
import akka.actor.ActorRef
import akka.actor.ActorRegistry
import akka.config.Supervision._
class SingleActor(val name: Integer) extends Actor {
self.lifeCycle = Permanent
self.faultHandler = OneForOneStrategy(List(classOf[Exception]), 30, 1000)
def receive = {
case num: Integer => {
if( num % 2 == 0 )
throw new Exception("This is a simulated failure, where does this get logged?")
println("Actor: " + name + " Received: " + num)
}
}
override def postStop(){
println("TestActor post Stop ")
}
override def preRestart(reason: Throwable){
println("TestActor "+ name + " restaring after shutdown because of " + reason)
}
override def postRestart(reason: Throwable){
println("Restaring TestActor "+name+"after shutdown because of " + reason)
}
}
object TestSingleActor{
def main(args : Array[String]) : Unit = {
println("starting TestSingleActor.main()")
val testActor = Actor.actorOf( new SingleActor(1) ).start()
println("number of actors: " + registry.actors.size)
printAllActorsInfo
(1 until 20 toList) foreach { testActor ! _ }
for( i <- 1 until 120 ){
Thread.sleep(500)
printAllActorsInfo
}
}
def printAllActorsInfo() ={
registry.actors.foreach( (a) =>
println("Actor hash: %d has mailbox %d isRunning: %b isShutdown: %b isBeingRestarted: %b "
.format(a.hashCode(),a.mailboxSize,a.isRunning,a.isShutdown,a.isBeingRestarted)))
}
}
我得到的输出如下：
[info] Running TestSingleActor
starting TestSingleActor.main()
Loading config [akka.conf] from the application classpath.
number of actors: 1
Actor hash: -1537745664 has mailbox 0 isRunning: true isShutdown: false isBeingRestarted: false
Actor: 1 Received: 1
Actor hash: -1537745664 has mailbox 17 isRunning: true isShutdown: false isBeingRestarted: false
... 117 more of these lines repeted ...
Actor hash: -1537745664 has mailbox 17 isRunning: true isShutdown: false isBeingRestarted: false
[info] == run ==
[success] Successful.
[info]
[info] Total time: 70 s, completed Aug 17, 2011 2:24:49 PM
答案 0 :(得分：5)
问题是我使用的是akka.conf文件。我使用的是参考1.1.3 akka.conf文件，除了配置事件处理程序的行。
我的（破碎的）： event-handlers = ["akka.event.slf4j.Slf4jEventHandler"]
参考1.1.3（有效的）：
event-handlers = ["akka.event.EventHandler$DefaultListener"]
使用我的事件处理程序配置行，不会发生Actor重启。参考1.1.3线路重启很奇妙。
我根据这些说明进行了此更改http://akka.io/docs/akka/1.1.3/general/slf4j.html
因此，通过删除该页面中的建议并返回到1.1.3参考akka.conf，我能够获得容错的Actors。
答案 1 :(得分：1)
我相信你的问题在发送消息后终止，你不是试图让你的异步应用程序保持活动状态，因此主线程退出，并用它来解决所有问题。