Graceful restart of gunicorn server

gunicorn_restart.py

# the idea is taken from here: http://unicorn.bogomips.org/SIGNALS.html

import os
import signal


# first we need to get the master process id
# it might be stored in a .pid file, e.g.
# let's assume we have the id in `master_pid`

# sending USR2 signal to the master process, this will recreate the master process and the worker(s)
os.kill(master_pid, signal.SIGUSR2)
# sending WINCH signal to the old master process
# can be skipped if the process is not daemonized
os.kill(master_pid, signal.SIGWINCH)
# sending the QUIT signal to the old master process
os.kill(master_pid, signal.SIGQUIT)