Q:

How do web servers like apache do things asynchronously? Does django have relative logic too?

I learn about being asynchronous when i write code with twisted, but i wonder now how do common web servers process thing asynchronously. As a case of this below:
apache get a client request from A, and there maybe some operations  block the main process. If apache doesn't do some tricks here, then at the just time another client B send 
a request , and obviously client B will get no response. Right? I guess, every client request will be processed in a dependent process/thread?
And django is a web framework, the question is whether django has the logic about "not blocking", or the work is handled totally by web servers. 

A:

There are no tricks here, really. Apache simply spins up multiple processes and/or threads (depending on how it is configured), and a request is routed to the next available one. 
The logic is exclusively in the web server.

