Test if a celery task is still being processed

Question

How can I test if a task (task_id) is still processed in celery? I have the following scenario:

1. Start a task in a Django view
2. Store the BaseAsyncResult in

Answer 1

define a field (PickledObjectField) in your model to store the celery task:

class YourModel(models.Model):
    .
    .
    celery_task = PickledObjectField()
    .
    .

    def task():
        self.celery_task = SubmitTask.apply_async(args = self.task_detail())
        self.save()

In case your task is not specific on any model you should create one specifically for the celery tasks.

or else I suggest using django-celery. It has a nice monitoring feature:
http://ask.github.com/celery/userguide/monitoring.html#django-admin-monitor, saves the tasks details in a django model in a nice graphical way.

Answer 2

I think there is a better way than to store a task object in the model. For example, in case you wanted to check if a group of task (parallel) have completed:

# in the script you launch the task
from celery import group

job = group(
    task1.s(param1, param2),
    task2.s(param3, param4)
)
result = job.apply_async()
result.save()

# save the result ID in your model
your_obj_model = YourModel.objects.get(id='1234')
your_obj_model.task_id = result.id
your_obj_model.save()

Then in your view

from celery.result import GroupResult
# ...
task_result = GroupResult.restore(your_obj_model.task_id)
task_finished = task_result.ready()
# will be True or False