> A preliminary patch is in attachment.
> By default it uses select() but looks for ValueError (raised in case 
> FD_SETSIZE gets hit) and falls back on using poll().
>
> This is the failure I get when running tests on Linux.
> It is related to issue 3321 and I'm not sure what to do with it (remove > the test maybe?).

I guess the patch could do

    if any(x[1] & POLLNVAL for x in ret):
        raise ValueError('invalid file descriptor')

Also, I don't think there is any need to unregister the fds since you are just removing entries from an internal dict which will be garbage collected.

I don't know if patching 2.7, 3.2, 3.3 to use/fallback on poll() would be allowed as a bug fix.  When, if ever, will the next 2.7 release happen?