I’m not sure I agree. accept() pops from a queue. You can wait—and-pop or you can pop-or-fail. I guess the former fits in a proactor model and the latter fits in a reactor model, but I think that distinction misses the point a bit. Accepting sockets works fine in either model.

It breaks down in a context where you do an accept that can be canceled and you don’t handle it intelligently. In a system where cancellation is synchronous enough that values won’t just disappear into oblivion, one could arrange for a canceled accept that succeeded to put the accepted socket on a queue associated with the listening socket, fine. But, in general, the operation “wait for a new connection and irreversibly claim it as mine IMO just shouldn’t be done in a cancellable context, regardless of whether it’s a “reactor” or a “proactor”. The whole “select and, as one option, irrevocably claim a new connection” code path in the OP seems suspect to me, and the fact that it seems to work under epoll doesn’t really redeem it in my book.