Ensuring one task of a kind is being executed at a time. (Multiple tasks of different kinds can be executed concurrentlly) celery python

Question

Let's say I have created two shared tasks:

from celery import shared_task

@shared_task
def taskA():
    #do something
    pass

@shared_task
def taskB():
    #do something else
    pass

I am using celery to perform certain tasks that will be invoked by the users of my Django project. I have no issue with taskA and taskB being executed at the same time. But, if taskA is already being executed, and another user tries to invoke taskA again, I want to show them an error message.

Is there a way to do that?

Answer 1

The only reliable way to do this that I can think of is to have a Celery worker with concurrency set to 1, subscribed to a dedicated queue. Then you send taskA to this particular queue.