I second the comment about open-ended computer science questions. I like to ask candidates what happens during a thread switch. Their responses allow me to prob

I second the comment about open-ended computer science questions. I like to ask candidates what happens during a thread switch. Their responses allow me to probe other areas of computing knowledge. What are the performance implications of locking? How can we make a networking application event-driven without threads? That really gives me a sense of whether the candidate keeps up-to-date with concepts like epoll() and libevent.