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一对一地重新启动Actors?我希望可以通过此文档完成此操作http://akka.io/docs/akka/1.1.3/scala/fault-tolerance
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LoadBalancer后面设置了5个Actors,它只打印出发送给它们的整数,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 . 我希望奇数会得到输出,但是在偶数偶数故障之后,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个演员开始,前5个偶数让他们破产,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,但是会在例外情况下使用一个经过处理的邮箱重新启动 . 我希望看到preRestart和postRestart的println . 需要在此代码示例中配置什么才能实现这些目标?
以下是关于akka和Actors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 . 我正在创建一个在偶数上抛出异常的actor . 路上没有负载均衡器或其他东西 . 我正在尝试打印出关于演员的信息 . 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怪的数字,但看起来Actor会在其邮箱中找到消息 .
我是否将OneForOneStrategy设置错误?我需要将Actor链接到某个东西吗?这种配置是否从根本上误导了我? Dispatcher是否需要设置容错,如何?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
2 回答
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,但配置事件处理程序的行除外 .
我的(破碎的):
参考1.1.3(有效的):
使用我的事件处理程序配置行,不会发生Actor重新启动 . 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 .
我相信你的问题在发送消息后终止,你不是试图保持你的异步应用程序活着,所以主线程退出,并用它来解决所有问题 .