> > What needs to happen to get recvmsg() supported in Python?
> 
> Well, I guess that the only reason is that no committer is motivated
> enough to bring this into Python: it's a rather large patch, and
> honestly, I'm not sure that many people are going to use it.
> The feature I personally like the most about sendmsg/recvmsg is the
> ability to do scatter-gather I/O, but if the performance is critical,
> then I won't be using Python.
> I know that sendmsg also has some other advantages (passing FDs,
> ancillary data...).

Modules/_multiprocessing already has code using sendmsg/recvmsg,
precisely to pass FDs IIRC.
Generic support for sendmsg() and recvmsg() in the socket module would
allow to rewrite that code in pure Python.