python3.6 在多线程中使用 tornado 时发生错误

Question

我只是简单地将 tornado 应用程序与线程一起使用，如下代码所示：

def MakeApp():
    return tornado.web.Application([(r"/websocket", EchoWebSocket), ])

def run_tornado_websocket():
    app = MakeApp()
    http_server = tornado.httpserver.HTTPServer(app, ssl_options={
        "certfile": os.path.join(os.path.abspath("."), "server.crt"),
        "keyfile": os.path.join(os.path.abspath("."), "server_no_passwd.key"),
        })

    http_server.listen(options.port)
    tornado.ioloop.IOLoop.current().start()

if __name__ == '__main__':
    threads = []
    t = threading.Thread(target=run_tornado_websocket, args=())
    threads.append(t)
    for t in threads:
        t.start()

它在 python3.5 上工作正常。但它在 python3.6 和持续的龙卷风上失败。它得到错误：

Exception in thread Thread-1:
Traceback (most recent call last):
  File "D:\python3\lib\threading.py", line 916, in _bootstrap_inner
    self.run()
  File "D:\python3\lib\threading.py", line 864, in run
    self._target(*self._args, **self._kwargs)
  File "D:\ssl\ws_server.py", line 49, in run_tornado_websocket
    http_server.listen(options.port)
  File "D:\python3\lib\site-packages\tornado\tcpserver.py", line 145, in listen
    self.add_sockets(sockets)
  File "D:\python3\lib\site-packages\tornado\tcpserver.py", line 159, in add_sockets
    sock, self._handle_connection)
  File "D:\python3\lib\site-packages\tornado\netutil.py", line 219, in add_accept_handler
    io_loop = IOLoop.current()
  File "D:\python3\lib\site-packages\tornado\ioloop.py", line 282, in current
    loop = asyncio.get_event_loop()
  File "D:\python3\lib\asyncio\events.py", line 694, in get_event_loop
    return get_event_loop_policy().get_event_loop()
  File "D:\python3\lib\asyncio\events.py", line 602, in get_event_loop
% threading.current_thread().name)
RuntimeError: There is no current event loop in thread 'Thread-1'.

我认为python3.6中的IOLOOP有一些变化。但我不知道如何解决这个问题，很想知道原因。

Answer 1

从 Tornado 5.0 开始，默认使用asyncio事件循环。 asyncio有一些额外的限制，因为在主线程以外的线程上启动事件循环是一种不常见的模式，而且经常是一个错误。 您必须通过asyncio.set_event_loop(asyncio.new_event_loop())告诉 asyncio 您想在新线程中使用事件循环，或使用asyncio.set_event_loop_policy(tornado.platform.asyncio.AnyThreadEventLoopPolicy())禁用此限制。