Hello world tornado working with circus

hello_world_circus.py

import sys
import socket
import tornado.ioloop
import tornado.web

class MainHandler(tornado.web.RequestHandler):
    def get(self):
        self.write("Hello, world")

application = tornado.web.Application([
    (r"/", MainHandler),
])

if len(sys.argv) > 1:
    fd = int(sys.argv[1])   # getting the FD from circus
    sock = socket.fromfd(fd, socket.AF_INET, socket.SOCK_STREAM)
    # sock.setblocking(0)

    from tornado.httpserver import HTTPServer
    server = HTTPServer(application)
    server.add_socket(sock)
else:
    application.listen(8888, address="0.0.0.0")

tornado.ioloop.IOLoop.instance().start()