Celery Periodic Tasks not running in Django

Question

file structure

proj/proj/
         celery.py
         (and other files)
    /sitesettings/
         tasks.py
         (and other files)

celery.py

app = Celery('mooncake',broker_url = 'amqp://')
app.config_from_object('django.conf:settings', namespace='CELERY')
app.autodiscover_tasks()

sitesettings/tasks.py

from __future__ import absolute_import, unicode_literals
from comma.models import Post
from mooncake.celery import app

app.conf.beat_schedule = {
'every-5-seconds': {
    'task': 'sitesettings.tasks.statisticsTag',
    'schedule': 5.0,
    'args': ()
},
}

@app.task
def statisticsTag():
    print(Post.objects.all()[0])

and run it with

celery -A proj beat -l info

it out put with

[2019-02-22 18:21:08,346: INFO/MainProcess] Scheduler: Sending due task every-5-seconds (sitesettings.tasks.statisticsTag)

but no further output. I used to try write it in proj/celery.py, but it cannot run cuz I have to import from another app, it exit with "app not loaded" error. So what should I do?

Answer 1

The command you are calling to start celery celery -A proj beat -l info is starting a beat scheduler instance of celery which sends due tasks to a worker instance.

You will also need to start a worker server that will execute those due tasks. You can start a celery worker with the command celery -A proj worker -l info. This will need to be running at the same time as your scheduler is running.

Alternatively you can run a worker with embedded beat scheduler celery -A proj worker -B -l info but that is not recommended for production use.