way to fix number of concurrent sessions allowed at app level. django
You're not asking about sessions, you're asking about requests. What you want is known as throttling. However, it would be quite difficult to do it inside the app, because Apache manages multiple processes and threads, so you'd need some external process to keep track of these in order to enable the throttling.
Basically, this sort of thing is best done within Apache itself, by something like mod_throttle.
How can I fix number of concurrent sessions allowed at app level?
Basically I want a  limit to how many concurrent requests to this url to keep the server from getting congested.
I guess some middleware hack?
Thanks.