lighttpd forum lighty > Limiting fcgi (Rails) concurrent connections per-IP

On an active server, Rails connections need to be throttled per IP, so a 
single user (or his all-too-common misbehaving robot) can't hog too many 
expensive Rails processes.  I can't find any way to do this in lighttpd 
or nginx.

This should be a throttle: if more than N connections from the same IP, 
stall the connection; when a connection from an IP finishes, start the 
next oldest one in the queue.

This is particularly important when there are long-running Rails 
requests.  It may apply to other systems, but Rails is a particular 
problem since it's so expensive to run more connections concurrently 
(since it's not threadsafe and has to spawn a whole new process each, 
eating way too much memory).

The limit may be very low, eg. 2-3 per IP.  This is much lower than a 
typical connection limit and should only apply to the limited Rails 
requests, not to static requests.

mod_evasive can't do this; it just drops connections with an error.