我正在尝试在Akka Actors中实现容错行为。我正在处理一些依赖于系统中Actor长时间运行的代码。我发现我的处理停止了几个小时(应该需要大约10个小时),并且没有太多的进展。我认为我的Actors无法从异常中恢复。
我需要做什么才能永久地使Actors按照一对一的方式重新启动? 我期望可以从这份文档http://akka.io/docs/akka/1.1.3/scala/fault-tolerance中完成此操作。
我正在使用akka 1.1.3和scala 2.9。
我认为这里发生的情况是5个演员开始表演,前五个偶数将它们淘汰并且它们无法重新开始。
如何更改此代码以使演员从异常中恢复?
我预计这实际上会打印出1到200之间所有的奇数。我认为每个演员都会在偶数上失败,但在异常时会被重启并保留其邮箱。我期望看到preRestart和postRestart的println。在此代码示例中需要进行哪些配置才能实现这些内容?
以下是关于akka和演员的其他假设,这可能导致我的误解。我假设可以使用监管者或故障处理程序对演员进行配置,以便在接收期间抛出异常时重新启动并继续可用。如果演员在接收期间抛出异常,则我假设发送给演员的消息将丢失。我假设调用抛出异常的演员的preRestart()和postRestart()方法。
代码示例代表了我正在尝试做的事情,并基于Why is my Dispatching on Actors scaled down in Akka?。
我得到的输出如下:
我需要做什么才能永久地使Actors按照一对一的方式重新启动? 我期望可以从这份文档http://akka.io/docs/akka/1.1.3/scala/fault-tolerance中完成此操作。
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 ! _ }
}
}
这段代码在负载均衡器后设置了5个Actor,这些Actor会打印发送给它们的整数,但是如果收到偶数则会抛出异常以模拟故障。将整数0至200发送给这些Actor。我期望奇数会被输出,但在几个偶数故障后,所有内容似乎都停止了。在使用sbt运行此代码时,输出如下:
[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
我认为这里发生的情况是5个演员开始表演,前五个偶数将它们淘汰并且它们无法重新开始。
如何更改此代码以使演员从异常中恢复?
我预计这实际上会打印出1到200之间所有的奇数。我认为每个演员都会在偶数上失败,但在异常时会被重启并保留其邮箱。我期望看到preRestart和postRestart的println。在此代码示例中需要进行哪些配置才能实现这些内容?
以下是关于akka和演员的其他假设,这可能导致我的误解。我假设可以使用监管者或故障处理程序对演员进行配置,以便在接收期间抛出异常时重新启动并继续可用。如果演员在接收期间抛出异常,则我假设发送给演员的消息将丢失。我假设调用抛出异常的演员的preRestart()和postRestart()方法。
代码示例代表了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。我正在启动一个演员,该演员在偶数时抛出异常,没有负载均衡器或其他东西阻碍。我尝试打印有关演员的信息。在消息发送到演员后,我等待一分钟退出程序并监视发生了什么。
我希望这将打印出奇数,但看起来演员坐在其邮箱中的消息周围。
我设置了OneForOneStrategy吗?我需要将Actor链接到某些内容吗?我的配置方式基本上是错的吗?是否需要设置具有容错能力的调度程序?我会弄乱调度程序中的线程吗?
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
[info] Running FaultTest starting FaultTest.main() Loading config [akka.conf] from the application classpath. Number of Actors: 5 Actor: 0 Received: 1 Actor: 4 Received: 3 Actor: 1 Received: 7 Actor: 1 Received: 9
,输出会暂停,但是其他数字不会打印。我没有等待应用程序退出,但是30-40秒后什么也没有发生。此外,如果我删除故障,则数字将非常快地打印出来,在不到2秒的时间内完成。 - Brian C.