title: How to detect too many messages? [Akka Actors]
body: <p>Any actor can get too much messages. How to detect such bottleneck?</p>
  
  <p>If it happen then how would look like the CPU usage? Would there be always at least 1 core on 100% usage or not?</p>
  
  <p>In Akka 1.x I could check length of message queue but is it unavailable in 2.x. How to deal with it now?</p>