> Perhaps you can just dup() the socket? That's what the ref counter is for IIRC.

I already dup them for loop.create_server(sock=sock) and loop.create_connection(sock=sock) cases.  Duping for sock_recv & friends will add too much overhead (they are relatively short operations).  Another argument against duping is that the number of open FDs is a limited OS resource.

So far Victor's idea of using '_io_refs' sounds like a perfect fit for both asyncio and uvloop.  After all, asyncio use case is very similar to `socket.makefile()` -- keep the socket object alive while another API relies on it.