Search code examples
akkajrubyshutdown

akka system.shutdown and awaitTermination

Following code is called at the very end of my program (it's written in JRuby):

@na.tell(PoisonPill) if defined? @na   # @na, @sa and @pe are Actors
@sa.tell(PoisonPill) if defined? @sa
@pe.tell(PoisonPill) if defined? @pe

@@system.shutdown    # @@system is the ActorSystem
@@system.awaitTermination

I found this approach here but I don't understand why it works.

Does awaitTermination wait for all Actors to terminate?

Isn't @@system shutted down before awaitTermination is called?

edit: I noticed that I doesn't even need to call tell(PoisonPill). I commented it out and it still works...

Solution

  • Okay I solved it now. When I call system.shutdown all actors terminate after their current task. That's not what I want because there could be more tasks in the queue.

    So I send a PoisonPill to each actor at the end of my main thread and then wait for them to terminate. I also use the function postStop in each actor to set a finished flag and shut down the system when all actors have finished.

    import Actors   # needed for Java-style poisonPill

actor1.tell(Actors::poisonPill)  # for Akka 2.0.0
actor2.tell(Actors::poisonPill)
system.awaitTermination