After seeing lighttpd grow to hundreds of megabytes I couldn’t sleep. It was like tiny chicken has grown into huge monster. After some experimenting I managed to grow monsters myself:

http://rotanovs.com/lighttpd/lighttpd_dos_tool

Basically the source of the problem is that lighttpd ignores max request size setting and reads data until it becomes huge and eats all available memory.

Return to Apache? No way. Lighttpd problems are usually solved lightning fast – so a little bit of patience and the cure will be ready.