Question

From the documentation I understood that sending a Kill message to an actor will restart it, but what actually happens is it just stops.

(Is the documentation out of date?)

Answer 1

Create a new top-level actor which in turn creates the old top-level actor in its preStart method. This will be the supervisor, and the supervisor strategy can be set by putting this code in the new top-level actor:

override val supervisorStrategy = OneForOneStrategy() {
  case _: Exception => Restart
  case _: Throwable => Escalate
}

The Kill message still needs to be sent to what was the old top-level actor.