在另一个演员中创建Akka演员

Question

I create an actor A. When I send a message to A, the receive method tries to create an actor B. When I run a piece of code that calls:

context.system.actorOf(Props[B], "B")

I get an exception:

InvalidActorNameException: actor name [B] is not unique!

Do you have any idea why this is happening?

Answer 1

Actor paths (part of which is the name that you pass to system.actorOf or context.actorOf , if you use the variants of actorOf that take a name) must be unique in an actor system. You're probably sending more than one message to actor A: every time actor A receives this message, it tries to create a top-level actor B with the name "B". Either drop the name altogether...

context.system.actorOf(Props[B])

...or add a unique identifier to the name. For example:

val uuid = java.util.UUID.randomUUID.toString
context.system.actorOf(Props[B], s"B-${uuid}")

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As a side note, top-level actors (ie, actors created via system.actorOf ) should be made sparingly, as the documentation advises:

Top-level actors are the innermost part of your Error Kernel, so create them sparingly and prefer truly hierarchical systems. This has benefits with respect to fault-handling (both considering the granularity of configuration and the performance) and it also reduces the strain on the guardian actor, which is a single point of contention if over-used.

If your intent is to create an actor B as a child of actor A every time the latter receives a message, then use context.actorOf .