Celery: how to add a callback function when calling a remote task (with send_task)

问题

You can use celery to call a task by name, that is registered in a different process (or even on a different machine):

celery.send_task(task_name, args=args, kwargs=kwargs)

(http://celery.readthedocs.org/en/latest/reference/celery.html#celery.Celery.send_task)

I now would like to be able to add a callback that will be executed as soon as the task finished and that will be executed within the process that is calling the task.

My Setup

I have a server A, that runs a django powered website and I use a basic celery setup as described here. I don't run a celery worker on server A.

Then there is server B, that runs (several) celery worker.

So far, this setup seems to work pretty good. I can send tasks on server A and they get executed on the remote server B.

The Problem

The only problem is, that I'm not able to add a callback function.

In the docs it says, that you can add a callback by providing a follow-up task. So I could do something like this:

@celery.task
def result_handler(result):
    print "YEAH"

celery.send_task(task_name, args=args, kwargs=kwargs, link=result_handler.s())

This however means, I have to start a worker on server A that registers the task "result_handler". And even if I do that, then the handler will be called in the process spawned by the worker and not the django process, that is calling the task.

The only solution I was able to come up with was an endless loop that checks every 2 seconds if the task is ready or not, but I think there should be a simpler solution.

来源：https://stackoverflow.com/questions/24367254/celery-how-to-add-a-callback-function-when-calling-a-remote-task-with-send-tas

标签

python

django

multiprocessing

celery