title: Are socket.io SERVER emit callbacks blocking?
body: <p>When an emit is received on the SERVER (i.e. generated by a client), does the callback function complete before the next emit is processed?</p>
  
  <p>Example:</p>
  
  <pre><code>socket.on('disconnect', function() {
      log('disconnect START - ' + socket.id);
  
      ...
      ...
      Do some stuff
      ...
      ...
  
      log('disconnect END - ' + socket.id);
  });
  </code></pre>
  
  <p>I seem to be getting this output in my log:</p>
  
  <pre><code>disconnect START - z0w0W4scKZ8o6c4nAAAm
  disconnect END - z0w0W4scKZ8o6c4nAAAm
  disconnect START - LLnSgRBV9NZ35mjrAAAk
  disconnect START - djl3hyNvIwAhSEDbAAAn
  disconnect END - LLnSgRBV9NZ35mjrAAAk
  disconnect END - djl3hyNvIwAhSEDbAAAn
  </code></pre>
  
  <p>As you can see, a START interrupts another before the END is reached...</p>