Print statement in Celery scheduled task doesn't appear in terminal

Question

When I run celery -A tasks2.celery worker -B I want to see "celery task" printed every second. Currently nothing is printed. Why isn't this working?

from app import app
from celery import Celery
from datetime import timedelta

celery = Celery(app.name, broker='amqp://guest:@localhost/', backend='amqp://guest:@localhost/')
celery.conf.update(CELERY_TASK_RESULT_EXPIRES=3600,)

@celery.task
def add(x, y):
    print "celery task"
    return x + y

CELERYBEAT_SCHEDULE = {
    'add-every-30-seconds': {
        'task': 'tasks2.add',
        'schedule': timedelta(seconds=1),
        'args': (16, 16)
    },
}

This is the only output after staring the worker and beat:

[tasks]
  . tasks2.add

[INFO/Beat] beat: Starting...
[INFO/MainProcess] Connected to amqp://guest:**@127.0.0.1:5672//
[INFO/MainProcess] mingle: searching for neighbors
[INFO/MainProcess] mingle: all alone

score 18 · Accepted Answer · answered Jul 15 '15 at 15:28

You wrote the schedule, but didn't add it to the celery config. So beat saw no scheduled tasks to send. The example below uses celery.config_from_object(__name__) to pick up config values from the current module, but you can use any other config method as well.

Once you configure it properly, you will see messages from beat about sending scheduled tasks, as well as the output from those tasks as the worker receives and runs them.

from celery import Celery
from datetime import timedelta

celery = Celery(__name__)
celery.config_from_object(__name__)

@celery.task
def say_hello():
    print('Hello, World!')

CELERYBEAT_SCHEDULE = {
    'every-second': {
        'task': 'example.say_hello',
        'schedule': timedelta(seconds=5),
    },
}

$ celery -A example.celery worker -B -l info

[tasks]
  . example.say_hello

[2015-07-15 08:23:54,350: INFO/Beat] beat: Starting...
[2015-07-15 08:23:54,366: INFO/MainProcess] Connected to amqp://guest:**@127.0.0.1:5672//
[2015-07-15 08:23:54,377: INFO/MainProcess] mingle: searching for neighbors
[2015-07-15 08:23:55,385: INFO/MainProcess] mingle: all alone
[2015-07-15 08:23:55,411: WARNING/MainProcess] celery@netsec-ast-15 ready.
[2015-07-15 08:23:59,471: INFO/Beat] Scheduler: Sending due task every-second (example.say_hello)
[2015-07-15 08:23:59,481: INFO/MainProcess] Received task: example.say_hello[2a9d31cb-fe11-47c8-9aa2-51690d47c007]
[2015-07-15 08:23:59,483: WARNING/Worker-3] Hello, World!
[2015-07-15 08:23:59,484: INFO/MainProcess] Task example.say_hello[2a9d31cb-fe11-47c8-9aa2-51690d47c007] succeeded in 0.0012782540870830417s: None

score 14 · Answer 2 · answered May 28 '18 at 21:02

In version 4.1.0 you have to add logger to your task.py file like so:

from celery.utils.log import get_task_logger

logger = get_task_logger(__name__)


@task(name="multiply_two_numbers")
def mul(x, y):
    total = x * (y * random.randint(3, 100))
    #HERE:
    logger.info('Adding {0} + {1}'.format(x, y))
    return total

Stated halfway down in the docs here if you want more info: http://docs.celeryproject.org/en/latest/userguide/tasks.html

The worker will automatically set up logging for you. – Florent Jan 19 '20 at 14:02 — Florent, Jan 19 '20 at 14:02

score 4 · Answer 3 · answered Sep 19 '22 at 17:27

I actually had issues printing mine on command prompt because I was using the wrong command but I found a link to a project which I forked Project

(If on Mac ) celery -A Project worker --loglevel=info
(If on Windows) celery -A Project worker -l info --pool=solo

gonz · Answer 4 · 2015-07-14T18:35:58.387

1

Make sure you run celery beat worker for scheduled tasks:

celery beat --app app.celery

Check the docs here: http://celery.readthedocs.org/en/latest/userguide/periodic-tasks.html#starting-the-scheduler

edited Jul 14 '15 at 18:35

answered Jul 14 '15 at 18:35

gonz

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I ran that with no luck – huhh hhbhb Jul 14 '15 at 20:54

score 0 · Answer 5 · edited Apr 03 '23 at 08:02

0

I know it's an old thread, but for those running into it... please check your app config. Make sure "TESTING" is set to "False". In my case it's a Flask APP, also I am updating the celery config with Flask app config

celery.conf.update(app.config)

but just make sure TESTING is not set to "True",

edited Apr 03 '23 at 08:02

Suraj Rao

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answered Apr 03 '23 at 07:51

Ozzie Ghani

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Print statement in Celery scheduled task doesn't appear in terminal

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