title: python socket.error: [Errno 98] Address already in use
body: <p>when i setup application.py, it shows that socket.error: [Errno 98] Address already in use.</p>
  
  <pre><code>Traceback (most recent call last):
  File "application.py", line 121, in &lt;module&gt;
  main()
  File "application.py", line 117, in main
  http_server.listen(options.port)
  File "/usr/local/lib/python2.7/site-packages/tornado-3.1-py2.7.egg/tornado/tcpserver.py", line 117, in listen
  sockets = bind_sockets(port, address=address)
  File "/usr/local/lib/python2.7/site-packages/tornado-3.1-py2.7.egg/tornado/netutil.py", line 90, in bind_sockets
  sock.bind(sockaddr)
  File "/usr/local/lib/python2.7/socket.py", line 224, in meth
  return getattr(self._sock,name)(*args)
  socket.error: [Errno 98] Address already in use
  </code></pre>