Antoine Pitrou <pitrou@free.fr> added the comment: Generally I doubt anyone is using the non-blocking semantics of the Python 3 I/O stack. People doing non-blocking I/O generally do it with sockets instead, which tend to reproduce quite literally the POSIX behaviour and error codes. ---------- versions: -Python 3.2, Python 3.3, Python 3.4, Python 3.5, Python 3.8 _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue13322> _______________________________________