I'm handwaving a little because I haven't actually built something like this yet.
But I imagine you'd add the per-job epoll to the global epoll with EPOLLONESHOT, so that once an event is reported, it is unregistered with the global epoll. Whatever thread received that event then owns the job. When that thread decides there's nothing more to do, it adds the job epoll back to the global epoll with EPOLLONESHOT again.
What do you mean by that? Take that per-job epoll out of the outer epoll?