I've ran into this before, and I've always wondered why programs don't just do this: when data gets added to a previously-empty output buffer, make the input non-blocking, and whenever a read comes back with EWOULDBLOCK, flush the output buffer and make the input blocking again. (Or in other words, always make sure the output buffer is flushed before waiting/going to sleep.) Wouldn't this fix the problem? Would it have any negative side effects?