asyncio + tornado.web python3.3以上で実行できます

asyncweb.py

import tornado.web
from tornado.platform.asyncio import AsyncIOMainLoop
import asyncio

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



AsyncIOMainLoop().install()
application = tornado.web.Application([
    (r"/", MainHandler),
])
application.listen(8888)

asyncio.get_event_loop().run_forever()