By far the easiest way to get similar behavior is to run your Django app via Gunicorn (proxied from Nginx). Gunicorn supports hot code reloading via SIGHUP, and it does so by forking and gracefully killing old processes.

If your requirements don't match gunicorn (not django, not python, etc) then you can use https://github.com/TimothyFitz/zdd a project I wrote to automate rewriting nginx config files to deal with changing proxied portfiles. To integrate any existing server, all you have to do is make it bind to port 0 (let the OS choose a port) and the write a foo.port file that contains the port number (like a pidfile). That's it.