How do I restart celery workers gracefully?

Question

While issuing a new build to update code in workers how do I restart celery workers gracefully?

Edit: What I intend to do is to something like this

Answer 1

celery multi start 1 -A proj -l info -c4 --pidfile=/var/run/celery/%n.pid
celery multi restart 1 --pidfile=/var/run/celery/%n.pid

http://docs.celeryproject.org/en/latest/userguide/workers.html#restarting-the-worker