This is probably a stupid question, but what exactly is a "non-blocking web server"? All web servers are technically non-blocking, arent they? otherwise how could they handle simultaneous connections? Apache2 achieves this using a combination of fork() and pthreads. How exactly are Tornado (and Twisted also) different? Do they just set a bunch of sockets to non-bocking mode, build an FD list (or equivalent), and then loop over that with one big select() sys call?
Where would you use a framework like these, and what advantages can they give you over Apache2 (or other popular servers)? Thanks