Django and Celery: Tasks not imported - django

Question

I am using Django with Celery to run two tasks in the background related to contacts/email parsing.
Structure is:
project
/api
/core
tasks.py
settings.py
settings.py file contains:
BROKER_URL = 'django://'
BROKER_BACKEND = "djkombu.transport.DatabaseTransport"
#celery
BROKER_HOST = "localhost"
BROKER_PORT = 5672
BROKER_USER = "guest"
BROKER_PASSWORD = "guest"
BROKER_VHOST = "/"
sys.path.append(os.path.dirname(os.path.basename(__file__)))
CELERY_IMPORTS = ['project.core.tasks']
import djcelery
djcelery.setup_loader()
# ....
INSTALLED_APPS = (
#...
'kombu.transport.django',
'djcelery',
)
tasks.py contains:
from celery.task import Task
from celery.registry import tasks
class ParseEmails(Task):
#...
class ImportGMailContactsFromGoogleAccount(Task):
#...
tasks.register(ParseEmails)
tasks.register(ImportGMailContactsFromGoogleAccount)
Also, added in wsgi.py
os.environ["CELERY_LOADER"] = "django"
Now, I have this app hosted on a WebFactional server. On my localhost this runs fine, but on the WebFaction server, where the Django app is deployed on a Apache server, I get:
2013-01-23 17:25:00,067: ERROR/MainProcess] Task project.core.tasks.ImportGMailContactsFromGoogleAccount[df84e03f-9d22-44ed-a305-24c20407f87c] raised exception: Task of kind 'project.core.tasks.ImportGMailContactsFromGoogleAccount' is not registered, please make sure it's imported.
But the tasks show up as registered. If I run
python2.7 manage.py celeryd -l info
I obtain:
-------------- celery#web303.webfaction.com v3.0.13 (Chiastic Slide)
---- **** -----
--- * *** * -- [Configuration]
-- * - **** --- . broker: django://localhost//
- ** ---------- . app: default:0x1e55350 (djcelery.loaders.DjangoLoader)
- ** ---------- . concurrency: 8 (processes)
- ** ---------- . events: OFF (enable -E to monitor this worker)
- ** ----------
- *** --- * --- [Queues]
-- ******* ---- . celery: exchange:celery(direct) binding:celery
--- ***** -----
[Tasks]
. project.core.tasks.ImportGMailContactsFromGoogleAccount
. project.core.tasks.ParseEmails
I thought it could be a relative import error, but I assumed the changes in settings.py and wsgi.py would prevent that.
I am thinking the multiple Python version supported by WebFactional could have to do with this, however I installed all the libraries for Python 2.7 and I am also running Django for 2.7, so there should be no problem with that.
Running in localhost using celeryd -l info the Tasks also show up in the list when I start the worker but it doesn't output the error when I call the task - it runs perfectly.
Thank you

Answer 1

I had the same issue in a new Ubuntu 12.04 / Apache / mod_wsgi / Django 1.5 / Celery 3.0.13 production environment. Everything works fine on my Mac Os X 10.8 laptop and my old server (which has Celery 3.0.12), but not on the new server.
It seems there is some issue in Celery:
https://github.com/celery/celery/issues/1150
My initial solution was changing my Task class based task to #task decorator based, from something like this:
class CreateInstancesTask(Task):
def run(self, pk):
management.call_command('create_instances', verbosity=0, pk=pk)
tasks.register(CreateInstancesTask)
to something like this:
#task()
def create_instances_task(pk):
management.call_command('create_instances', verbosity=0, pk=pk)
Now this task seems to work, but of course I've to do some further testing...