One reason: I am using clisp, which has no real thread support. The other lisps use too much resources. And I have a very limited amount of threads. I am not a server admin of a huge server, I have to work with one of these tiny-low-cost-virtual-servers, which have very limited resources.
As far as I see at the moment, connection-listener could be useful, but since clisp has no stable thread support yet, while usocket does not have support for accepting connections on server-sockets without blocking (and clisp does), which may be the reason why you decided to use two threads instead of only one loop for accepting and processing. I would have to write stuff arount it, anyway. So it is maybe easier for me to just implement an own little HTTP-Server, though it is not trivial.
Hi, If you decide to go with building your own simple http server, I will recommend you to look at mongrels parser. It's written in ragel but it's really trivial to use/import in Lisp (I did it for SBCL FFI, and it was damn easy, around 60 lisp lines or so) and it's pretty fast and secure. Just my 2 cents.
Cheers, V. Seguí