title: How to know if an actor is idle
body: <p>I have an unknown number of jobs to be executed by a known (of course) number of actors. The initial jobs number might increase after an actor completes a job. That is, an actor, upon completion of its task, might add a new job to be executed.</p>
  
  <p>The way I am handling this is to have each actor send a message back to the master when it completes its job, not only with the result of the execution but also with a 'flag' indicating that the actor is now idle. The master has a queue of jobs and a queue of idle actors, whenever an actor sends a 'job completed message' the master will check if there's something else for that actor to do... so on and so forth until the jobs' queue is empty and the idles' queue is full... at that point I shutdown the system. There's no much supervision here, so I feel that I am not doing it properly...</p>
  
  <p>I am not using a router because I could not find a way to query the router for idle actors, so my question is:</p>
  
  <p>What is the 'proper' way to handle the situation I have described above in Akka?</p>