新手请问,如何在tcp server中使用tornado.gen.coroutine

tcp server的代码如下:

#! /usr/bin/env python
#coding=utf-8

from tornado.tcpserver import TCPServer
from tornado.ioloop import IOLoop
from tornado.gen import *
class TcpConnection(object):
    def __init__(self,stream,address):
        self._stream=stream
        self._address=address
        self._stream.set_close_callback(self.on_close)
        self.send_messages()


    @coroutine
    def send_messages(self):
        yield self.send_message(b'hello \n')
        response1 = yield self.read_message()
        print(response1)
        yield self.send_message(b'world \n')
        print((yield self.read_message()))

    def read_message(self):
        self._stream.read_until(b'\n')

    def handle_message(self,data):
        print(data)

    def send_message(self,data):

        self._stream.write(data)

    def on_close(self):
        print("the monitored %d has left",self._address)

class MonitorServer(TCPServer):

    def handle_stream(self,stream,address):
        print("new connection",address,stream)
        conn = TcpConnection(stream,address)

if  __name__=='__main__':
    print('server start .....')
    server=MonitorServer()
    server.listen(20000)
    IOLoop.instance().start()

代码运行到yield self.send_message(b'hello \n')这一行,后面的代码就没有执行了,要怎么样才能解决这个问题啊?如果有其他类似的tcp server中使用tornado.gen.coroutine的例子,请告之我,谢谢!!

---

read_message 也要用 coroutine 修饰 他也是一个异步方法（要传 callback 的）