Bill Stewart writes:

The main failure mode seems to have been misconfigured clients grabbing the single-threaded server for a long time; it may be worth using a multi-threaded server, or alternatively a single-threaded server that has a fast timeout for how long it will talk to a client.

Single-user is just plain silly. With a fast timeout you still have problems with misconfigured clients hogging the server and legitimate clients that are running a little slow will also have problems. The server in the second challenge did have a fast timeout (it was too fast to easily query the server by hand, for instance) and it still wasn't adequate. I can't imagine making the timeout smaller. multi-user is the only way to go... andrew