Akka Typed ActorSelection/Receptionist

Question

I have question about ActorSelection/Receptionist in new Akka Typed.....

Before Akka Typed I didn't use ActorSelection because I read somewhere that it was not performant so I kept reference to the actor over HashMaps, now I am reading the documentation of the Akka Typed, I see that another mechanism Receptionist exist, so for me the question is, does it also suffers the same problems ActorSelection and I should stick to my old pattern of keeping reference to Actor over HashMap or now the receptionist is the way to go....

My specific scenario, my Actor spawns several Child Actors creates several Child Actors, if the parent Actor passivates or restored over Akka Persistence, it should again find reference to these Child Actors....

So what do you think, would I experience Performance problems if I convert to Receptionist?????

Thx for answers...

Answer 1

ActorSelection will resolve the actor path to an ActorRef each time you use it, this is somewhat costly, if used for a high throughput actor but has the upside that if the actor is stopped, and then later a new actor is started at the same path, the ActorSelection will deliver messages to the new actor, while if you had an ActorRef it specifically points to the actor instance that is no stopped and messages end up in dead letters.

The receptionist is quite different and is more like a registry of actors that you can subscribe to. When the set of ActorRefs registered for a key changes you get an update message with the new set, there is no extra overhead per message sent, you are dealing directly with the ActorRefs of the recipients.

Note that you can use the GroupRouter for delivery to actors registered with the receptionist and to avoid having to implement the subscription part in your actor.