Charles-François Natali added the comment:
> Guido van Rossum added the comment:
>
> I think you're looking for the discussion in issue 19017.
>
> IIRC the conclusion is that not only do you not get the same error
> everywhere, but you get it at different points -- sometimes register() of a
> bad FD passes and then [Selector.]select() fails, other times register() of a
> bad FD fails; when the FD is initially good and then gets closed, sometimes
> select() may fail, sometimes select() will silently ignore the FD. Sometimes
> unregister() of a closed FD will return False, sometimes True.
>
> Another consequence is that registering an FD, then closing it, then calling
> select(), then reopening it may keep reporting events for the FD or not.
Exactly, it's a mess.
> I think these are all things to call out in a section on caveats or common
> bugs.
What I don't remember was the conclusion: do we want to keep the
current OS-specific behavior, or do we want to try to be tolerant with
misuse?
For example, one possibility would be to ignore errors when
unregistering a file descriptor from epoll: for example, the
selectmodule currently ignore EBADF when unregistering a FD:
"""
case EPOLL_CTL_DEL:
/* In kernel versions before 2.6.9, the EPOLL_CTL_DEL
* operation required a non-NULL pointer in event, even
* though this argument is ignored. */
Py_BEGIN_ALLOW_THREADS
result = epoll_ctl(epfd, op, fd, &ev);
if (errno == EBADF) {
/* fd already closed */
result = 0;
errno = 0;
}
"""
IIRC libev and libevent both ignore those errors.
We have to settle on a solution before documenting it.
----------
_______________________________________
Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue19876>
_______________________________________
_______________________________________________
Python-bugs-list mailing list
Unsubscribe:
https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
