title: How heavy are akka actors?
body: <p>I am aware this is a very imprecise question and might be deemed inappropriate for stackoverflow. Unfortunately smaller applications (in terms of the number of actors) and 'tutorial-like' ones don't help me develop intuition about the overhead of message dispatch and a swift spot for granularity between a 'scala object' and a 'CORBA object'.</p>
  
  <p>While almost certainly keeping a state of conversation with a client for example deserves an actor, in most real use cases it would involve conditional/parallel/alternative interactions modeled by many classes. This leaves the choice between treating actors as facades to quite complex services, similar to the justly retired EJB, or akin to smalltalk objects, firing messages between each other willy-nilly whenever communication can possibly be implemented in an asynchronous manner.</p>
  
  <p>Apart from the overhead of message passing itself, there will also be overhead involved with lifecycle management, and I am wary of potential problems caused by chained-restarts of whole subtrees of actors due to exceptions or other errors in their root.</p>
  
  <p>For the sake of this question we may assume that vast majority of the communication happens within a single machine and network crossing is insignificant.</p>