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Celery get() works in python shell but not in Django view

I want to check basic Celery functionality inside official demo Celery project for django with code available here.

My modification is the demoapp/views.py (and of course urls.py to point to this view):

from __future__ import absolute_import, unicode_literals
from django.http import HttpResponse
from demoapp.tasks import add, mul, xsum


def home(request):
return HttpResponse("Your output is: %s" % mul.delay(22,4).get(timeout=1) )


which always gives timeout error, though the terminal of running Celery worker shows that task was received and displays correct return value.

However, if I start python shell python ./manage.py shell and then run

python ./manage.py shell

from demoapp.tasks import add, mul, xsum
mul.delay(22,4).get(timeout=1)


I immediately get the expected result. What may be the problem?

Rabbitmq server is running, I use Celery 4.2.1, django 2.0.6.

demoapp/tasks.py:

from __future__ import absolute_import, unicode_literals
from celery import shared_task


@shared_task
def add(x, y):
return x + y


@shared_task
def mul(x, y):
return x * y


@shared_task
def xsum(numbers):
return sum(numbers)


proj/celery.py:

from __future__ import absolute_import, unicode_literals
import os
from celery import Celery

# set the default Django settings module for the 'celery' program.
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'proj.settings')

app = Celery('proj')

# Using a string here means the worker doesn't have to serialize
# the configuration object to child processes.
# - namespace='CELERY' means all celery-related configuration keys
# should have a `CELERY_` prefix.
app.config_from_object('django.conf:settings', namespace='CELERY')

# Load task modules from all registered Django app configs.
app.autodiscover_tasks()


@app.task(bind=True)
def debug_task(self):
print('Request: {0!r}'.format(self.request))


proj/settings.py

...
CELERY_BROKER_URL = 'amqp://guest:guest@localhost//'
CELERY_ACCEPT_CONTENT = ['json']
CELERY_RESULT_BACKEND = 'db+sqlite:///results.sqlite'
CELERY_TASK_SERIALIZER = 'json'
...


1 Answer
1

Problem solved by installing result backend as stated at the bottom of this page.

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