That example is correct, this is how we use this with PHP since it can only handle one connection at the time, with a pool nginx divides it between its nodes, obviously the cgi part of php needs to run multiple times as well as its limit is per instance for most applications, but if your backend is none-blocking you can connect as much as you like.
The same goes for Lua and its co-sockets, embedded in nginx you have maximum none-blocking performance.
The same goes for Lua and its co-sockets, embedded in nginx you have maximum none-blocking performance.