平时碰见的问题|Python3.8 tornado报错NotImplementedError(转载)

以前都是装的3.7版本,没注意这次装了3.8,一直报这个错。正一筹莫展搜到这篇文章,原来是3.8版本才有的问题
之前的代码拿过来跑,遇到报错如下:
Traceback (most recent call last):
File ".\index.py", line 325, in
app.listen(8888)
File "C:\Program Files\Python38\lib\site-packages\tornado\web.py", line 2112, in listen
server.listen(port, address)
File "C:\Program Files\Python38\lib\site-packages\tornado\tcpserver.py", line 152, in listen
self.add_sockets(sockets)
File "C:\Program Files\Python38\lib\site-packages\tornado\tcpserver.py", line 165, in add_sockets
self._handlers[sock.fileno()] = add_accept_handler(
File "C:\Program Files\Python38\lib\site-packages\tornado\netutil.py", line 279, in add_accept_handler
io_loop.add_handler(sock, accept_handler, IOLoop.READ)
File "C:\Program Files\Python38\lib\site-packages\tornado\platform\asyncio.py", line 99, in add_handler
self.asyncio_loop.add_reader(fd, self._handle_events, fd, IOLoop.READ)
File "C:\Program Files\Python38\lib\asyncio\events.py", line 501, in add_reader
raise NotImplementedError
NotImplementedError

是由于 python3.8 asyncio 在 windows 上默认使用 ProactorEventLoop 造成的,而不是之前的 SelectorEventLoop。jupyter 依赖 tornado,而 tornado 在 window 上需要使用 SelectorEventLoop,所以产生这个报错.
请看官方文档:https://www.tornadoweb.org/en/stable/index.html#installation
【平时碰见的问题|Python3.8 tornado报错NotImplementedError(转载)】解决方法是,在 tornado开始执行前添加以下代码,在windows下单独处理:

# windows 系统下 tornado 使用 使用 SelectorEventLoop import platformif platform.system() == "Windows": import asyncioasyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())

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