I know bluehost.com "sort of" does this. If you use more then x % of the total CPU or memory of the server, then your account will be limited automatically. (A page is displayed saying that the page you're trying to view can't be displayed because it is using too much resources.) Does anyone know how they do this?
You need to build your own custom application to do this. So far I have not come across any sites that offer such solutions yet
I can't think of any standard apache modules that do this off of the top of my head. I know of ones that will limit ip connections from a specific ip, or throttle bandwidth from a specific site. But I cannot think of anyones that will do anything about cpu load. So I'm thinking you'd be looking at a custom cPanel addon.
There can't be any limit. But they monitor their servers closely...lol. There are few Linux Utils. available which notify you if certain process/user has maxed out the limit.
Well, I've found this a very vague and undercover issue...such solutions aren't that easy to find for mainstream widespead use!