python - Django Celery get task count

Question

I am currently using django with celery and everything works fine.

However I want to be able to give the users an opportunity to cancel a task if the server is overloaded by checking how many tasks are currently scheduled.

How can I achieve this ?

I am using redis as broker.

I just found this : Retrieve list of tasks in a queue in Celery

It is somehow relate to my issue but I don't need to list the tasks , just count them :)

Answer 1

Here is how you can get the number of messages in a queue using celery that is broker-agnostic.

By using connection_or_acquire, you can minimize the number of open connections to your broker by utilizing celery's internal connection pooling.

celery = Celery(app)

with celery.connection_or_acquire() as conn:
    conn.default_channel.queue_declare(
        queue='my-queue', passive=True).message_count

You can also extend Celery to provide this functionality:

from celery import Celery as _Celery


class Celery(_Celery)

    def get_message_count(self, queue):
        '''
        Raises: amqp.exceptions.NotFound: if queue does not exist
        '''
        with self.connection_or_acquire() as conn:
            return conn.default_channel.queue_declare(
                queue=queue, passive=True).message_count


celery = Celery(app)
num_messages = celery.get_message_count('my-queue')