python - How to use Tornado.gen.coroutine in TCP Server? -

i write tcp server tornado. here code:

#! /usr/bin/env python #coding=utf-8  tornado.tcpserver import tcpserver tornado.ioloop import ioloop 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()       def send_messages(self):         self.send_message(b'hello \n')         print("next")         self.read_message()          self.send_message(b'world \n')          self.read_message()       def read_message(self):         self._stream.read_until(b'\n',self.handle_message)      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() 

and face eorror assert self._read_callback none, "already reading",i guess eorror because multiple commands read socket @ same time.and change function send_messages tornado.gen.coroutine.here code:

@gen.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())) 

but there other errors. code seem stop after yield self.send_message(b'hello \n'),and following code seem not execute. how should ? if you're aware of tornado tcpserver (not http!) code tornado.gen.coroutine,please tell me.i appreciate links!

send_messages() calls send_message() , read_message() yield, these methods not coroutines, raise exception.

the reason you're not seeing exception called send_messages() without yielding it, exception has go (the garbage collector should notice , print exception, can take long time). whenever call coroutine, should either use yield wait finish, or ioloop.current().spawn_callback() run coroutine in "background" (this tells tornado not intend yield coroutine, print exception occurs). also, whenever override method should read documentation see whether coroutines allowed (when override tcpserver.handle_stream() can make coroutine, __init__() may not coroutine).

once exception getting logged, next step fix it. can either make send_message() , read_message() coroutines (getting rid of handle_message() callback in process), or can use tornado.gen.task() call coroutine-style code coroutine. recommend using coroutines everywhere.