title: "Who's Online" using Devise in Rails
body: <p>Using Devise on Rails, is there some way to list all the users who currently have active sessions i.e. the users that are currently logged in?</p>
  
  <p>Ps. I'm looking for a robust solution, not something simplistic like the ones in <a href="https://stackoverflow.com/questions/3184973/rails-using-devise-to-show-online-users">this question</a></p>