from threading import Thread
from tornado import ioloop, web

class MyHandler(web.RequestHandler):
    def get(self):
        self.write("hi back")

def app_in_thread():
    import asyncio
    asyncio.set_event_loop(asyncio.new_event_loop())
    app = web.Application(
        [('/hello', MyHandler)]
    )
    app.listen(9999)
    ioloop.IOLoop.current().start()

t = Thread(target=app_in_thread)
t.start()