This is my first time to create an issue on the python bug tracker so let me know if I don't follow the rule which I need to follow.

# Summary

Using 'loop.sock_connect' with 'asyncio.wait_for' raises 'OSError [WinError 10038]' in Windows 10 Pro when timed-out.

# Detail

I use 'loop.sock_connect' to establish a TCP connection for checking if a particular port on a target host is available.
However, when I wrap the coroutine with 'asyncio.wait_for', the following exception is raised when the wrapped coroutine has timed-out.

    Traceback (most recent call last):
      File "C:\Users\alisue/test.py", line 41, in <module>
        loop.run_until_complete(test(loop))
      File "C:\Python36\lib\asyncio\base_events.py", line 454, in run_until_complete
        self.run_forever()
      File "C:\Python36\lib\asyncio\base_events.py", line 421, in run_forever
        self._run_once()
      File "C:\Python36\lib\asyncio\base_events.py", line 1395, in _run_once
        event_list = self._selector.select(timeout)
      File "C:\Python36\lib\selectors.py", line 323, in select
        r, w, _ = self._select(self._readers, self._writers, [], timeout)
      File "C:\Python36\lib\selectors.py", line 314, in _select
        r, w, x = select.select(r, w, w, timeout)
    OSError: [WinError 10038] ...........

While it is raised from 'lib\selectors.py', I cannot catch this exception so the event loop has halted.

The attached 'test.py' is a minimum script to reproduce the error.

Thanks.

I should have mentioned that the script works well on macOS and Linux.
This issue exists only on Windows.

I've found an workaround. The point is that 'with s' should be included in a coroutine which will be timed-out.

    import asyncio
    import socket

    ADDR = ('10.0.2.1', 22)


    async def check(loop):
        s = socket.socket(socket.AF_INET,
                        socket.SOCK_STREAM)
        s.setblocking(False)
        with s:
            await loop.sock_connect(s, ADDR)


    async def test(loop):
        try:
            await asyncio.wait_for(
                check(loop),
                timeout=3,
                loop=loop,
            )
        except Exception as e:
            print('Fail: %s' % e)
        else:
            print('Success')


    if __name__ == '__main__':
        loop = asyncio.get_event_loop()
        loop.run_until_complete(test(loop))

I use the following patch to fix the behavior in Windows.


```
import sys

if sys.platform != 'win32':
    def patch():
        pass
else:
    def patch():
        """Patch selectors.SelectSelector to fix WinError 10038 in Windows

        Ref: https://bugs.python.org/issue33350
        """

        import select
        from selectors import SelectSelector

        def _select(self, r, w, _, timeout=None):
            try:
                r, w, x = select.select(r, w, w, timeout)
            except OSError as e:
                if hasattr(e, 'winerror') and e.winerror == 10038:
                    # descriptors may already be closed
                    return [], [], []
                raise
            else:
                return r, w + x, []

        SelectSelector._select = _select
```

https://github.com/python/asyncio/pull/419

It seems the PR above which has not merged solve the issue.

What Python version do you use?

I'm using python 3.7.2. And I met the same problem.

updated: I tried the test.py and it didn't show this error. So I think what I got is not the same problem as issue33350 although it shows the same traceback message.