# https://github.com/python/cpython/blob/v3.8.0/Lib/selectors.py#L312- L317 rs, ws, xs = select.select(to_read, to_write, to_write) ws = ws + xs except getattr(errno, "WSAENOTSOCK", errno.EBADF): rs, _, _ = select.select([self._waker_r.fileno()], [], [], 0) if rs: ws = [] else: call_soon_threadsafe(self._handle_select, rs, ws) def _handle_select( self, rs: List["_FileDescriptorLike"], ws: List["_FileDescriptorLike"] ) -> None: for r in rs: self._handle_event(r