The patch looks good, however there's something really bothering me:
in issue #14635, the same type of patch was applied to telnetlib,
here, it's multiprocessing and AFAICT, any single use of select() in
the standard library is subject to this FD_SETSIZE limitation.
That why I think it could probably be a good idea to expose a
high-level "selector" object in the select module, which would use the
"right" syscall transparently (e.g. select, poll or /dev/poll), with a
unified API. This would make writing portable and efficient I/O
multiplexing code much easier, not only in the stdlib, but also for
end-users.