title: Can we have global state in actor-based systems?
body: <p>One of the biggest advantages of the actor model is the removal of locking (actors operate independently and serially). Does this mean that we cannot have any shared/global state at all in an actor system (because accessing/updating that will bring in locks)? </p>
  
  <p>In more practical terms, what happens to updates to an entity (e.g. DB) from multiple actors in such a system?</p>