title: How do I find out who is connected to ActionCable?
body: <p>I have seen <code>ActionCable.server.open_connections_statistics</code>, <code>ActionCable.server.connections.length</code>, <code>ActionCable.server.connections.map(&amp;:statistics)</code>, <code>ActionCable.server.connections.select(&amp;:beat).count</code> and the like, however this is only "per process" (server, console, server worker, et cetera).  How do I find out <em>everyone</em> who is subscribed to ActionCable at this time?  This should return the same value on any Rails process in each environment (development, staging, production).  So for example, in development console you can also see the connections on the development server since they, in theory, use the same subscription adapter (redis, async, postgres).</p>
  
  <p>Rails 5.0.0.beta3, Ruby 2.3.0</p>
  
  <p>related <a href="https://stackoverflow.com/questions/32905259/actioncable-how-to-display-number-of-connected-users">ActionCable - how to display number of connected users?</a></p>