[Django]-How do I restart celery workers gracefully?

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

You can do:

celery multi restart w1 -A your_project -l info  # restart workers

Example

If you’re going the kill route, pgrep to the rescue:

kill -9 `pgrep -f celeryd`

Mind you, this is not a long-running task and I don’t care if it terminates brutally. Just reloading new code during dev. I’d go the restart service route if it was more sensitive.

You should look at Celery’s autoreloading

What should happen to long running tasks? I like it this way: long running tasks should do their job. Don’t interrupt them, only new tasks should get the new code.

But this is not possible at the moment: https://groups.google.com/d/msg/celery-users/uTalKMszT2Q/-MHleIY7WaIJ

I have repeatedly tested the -HUP solution using an automated script, but find that about 5% of the time, the worker stops picking up new jobs after being restarted.

A more reliable solution is:

stop <celery_service>
start <celery_service>

which I have used hundreds of times now without any issues.

From within Python, you can run:

import subprocess
service_name = 'celery_service'
for command in ['stop', 'start']:
    subprocess.check_call(command + ' ' + service_name, shell=True)

If you’re using docker/docker-compose and putting celery into a separate container from the Django container, you can use

docker-compose kill -s HUP celery

, where celery is the container name. The worker will be gracefully restarted and the ongoing task is not brutally stopped.

Tried pkill, kill, celery multi stop, celery multi restart, docker-compose restart. All not working. Either the container is stopped abruptly or the code is not reloaded.

I just want to reload my code in the prod server manually with a 1-liner. Don’t want to play with daemonization.

Might be late to the party. I use:

sudo systemctl stop celery

sudo systemctl start celery

sudo systemctl status celery