tornado4 的异步究竟怎么玩？

# coding:utf-8

import tornado.ioloop
import tornado.web
from tornado.gen import coroutine
from tornado.web import asynchronous
import tasync


class MainHandler(tornado.web.RequestHandler):
    @coroutine
    #@asynchronous
    def get(self):
        print('Hi')
        result = yield tasync.async()
        self.write("%s" % result )

class MainHandler2(tornado.web.RequestHandler):
    def get(self):
        self.write('test')

application = tornado.web.Application([
    (r"/", MainHandler),
    (r"/a", MainHandler2),
])

if __name__ == "__main__":
    application.listen(8888)
    print('Started.')
    tasync.init()
    tornado.ioloop.IOLoop.instance().start()

# coding:utf-8

import time
import threading
from functools import partial
from tornado.ioloop import IOLoop
from tornado.concurrent import Future

count = 1
future_dict = {}

def async(*args, **kwargs):
    global count
    future = Future()
    callback = kwargs.pop("callback", None)
    if callback:
        IOLoop.instance().add_future(future, lambda future: callback(future.result()))

    future_dict[count] = [future, time.time()]
    count += 1

    return future


def init():
    interval = 0.3
    io_loop = IOLoop.instance()

    def the_loop():
        while True:
            t = time.time()
            for k, v in future_dict.items():
                if t - v[1] >= 5:
                    io_loop.add_callback(_on_result, k, v[0])
                    del future_dict[k]
            time.sleep(interval)

    threading.Thread(target=the_loop, args=()).start()


def _on_result(result, future):
    print(result, time.time())
    future.set_result(result)