title: Sinatra + Fibers + EventMachine
body: <p>I would like to know to to pause a Root Fiber in ruby (if possible).</p>
  
  <p>I have this Sinatra app, and I am making async calls to an external API with EventMachine.
  I don't want to respond to the client until the api responds me.</p>
  
  <p>For example, sleeping the Root Fiber in Sinatra until the EventMachine callback wake it up.</p>
  
  <p>Thanks.</p>