Any state that could be accessed or modified concurrently is effectively distributed (in the Actor model). (If not over the network, then over multiple CPUs com

Any state that could be accessed or modified concurrently is effectively distributed (in the Actor model). (If not over the network, then over multiple CPUs communicating over a bus which may require memory barriers.) Unfortunately the model mandates that you must either a) implement ALL of your cohesive/non-concurrent state in "one actor per unit of cohesion" or b) deal with state as if it's distributed. In other words: It's not a good tradeoff for typical programs. (Which I think is what my original comment said.) Don't get me wrong: If almost all your state is distributed, e.g. Riak, then I'm sure it's a fine way to do things. Let's just avoid the "works-for-them-It's-sure-to-work-for-us" pitfall.