在 Akka 中，当一条消息被发送到一个 Actor Pool 时，'self' 是否持有对 Actor 实例或整个 Pool 的引用？

Question

如果我向一个 Actor 池发送一条消息，然后该 Actor 在收到该消息后向 self 发送一条消息，会发生什么情况？在这种情况下，发送到 self 是将消息发送到池中，还是发送到发送消息的特定 Actor 实例？

这个场景的伪代码如下所示

...
val system: ActorSystem = ActorSystem()
val actorPool: ActorRef = system.actorOf(
  Props(new SomeActor(someDependency))
    .withRouter(RoundRobinPool(conf.someActorPoolSize))
actorPool ! "hello"

class SomeActor(someDependency: SomeDependency) extends Actor {
  def receive = {
    case hello @ "hello" => self ! hello + " world"
    // ^Does the above send to the entire Pool, or does this specific
    // Actor just send the message directly to itself?
    case msg @ "hello world" => println(msg)
    // ^Do I know that the same Actor insntance that sent me "hello world"
    // is also going to execute "println(msg)", or could any Actor in the
    // Pool have sent the "hello world" message?
  }
}

Answer 1

self总是指向演员自己的ActorRef:

def receive = {
  case hello @ "hello" =>
    self ! hello + " world" // sends "hello world" to itself
  case msg @ "hello world" =>
    println(msg)

当路由发送 "hello world" 到 self 时，它会将那个字符串发送给自己。这个 "hello world" 字符串将在 case msg @ "hello world" => 子句中被捕获，actor 将打印消息。

Do I know that the same Actor insntance that sent me "hello world" is also going to execute "println(msg)"...

外部参与者可以向路由器发送 "hello" 或 "hello world"。然后，路由器会将消息转发到其中一个路由。对于确定 "hello world" 消息是来自自身还是外部参与者的路由，路由必须检查 sender 的值（例如，它可以检查 sender 是否等于self).

...or could any Actor in the Pool have sent the "hello world" message?

不清楚你在这里问什么。 Routees 通常不相互通信。

How would I send a message back to the Pool, instead of to 'self'? Would I need to pass the reference to the Actor Pool as a dependency, even though my Actor is a member of the Pool it wants to send messages to?

路由不需要了解其他路由或路由器。如果您想将消息发送回池中，请让原始发送者（即，将消息发送到 router 的参与者）执行此操作。换句话说，让你的 routee 将消息发送到 sender，然后让那个 actor 将消息发送回路由器。为了强调这一点，sender 在这种情况下不是 router/pool，而是原始发件人（对此有一些例外，如 documentation):

client            --> router --> [routee1, routee2, etc.]
(original sender)                // sender in a routee is a reference to client, because
                                 // the router forwards the messages to the routees

您可以阅读有关路由的更多信息 here。

在 Akka 中，当一条消息被发送到一个 Actor Pool 时，'self' 是否持有对 Actor 实例或整个 Pool 的引用？

In Akka, when a message is sent to an Actor Pool, does 'self' hold a reference to the Actor instance or to the entire Pool?

concurrency

scala

actor

akka