Question

If I call context.watch() on an ActorRef that is already dead, am I guaranteed to still receive a termination message?

Also, after having received a termination message regarding a specific actor, do I still need to call unwatch()?

Also, are watch() calls reference counted? If I call watch() twice, followed by unwatch() once, am I guaranteed to still get termination messages?

Answer 1

I think the documentation is pretty clear:

“One important property is that the message will be delivered
irrespective of the order in which the monitoring request and target’s
termination occur, i.e. you still get the message even if at the time
of registration the target is already dead.”

• http://doc.akka.io/docs/akka/2.0.1/general/supervision.html

And, you do not need to unwatch since the actor can’t die twice, and it’s not reference counted. It’s binary.

Cheers,
√