[task] Deleting all pending tasks in celery / rabbitmq

In Celery 3+

http://docs.celeryproject.org/en/3.1/faq.html#how-do-i-purge-all-waiting-tasks

CLI

Purge named queue:

 celery -A proj amqp queue.purge <queue name>

Purge configured queue

celery -A proj purge

I’ve purged messages, but there are still messages left in the queue? Answer: Tasks are acknowledged (removed from the queue) as soon as they are actually executed. After the worker has received a task, it will take some time until it is actually executed, especially if there are a lot of tasks already waiting for execution. Messages that are not acknowledged are held on to by the worker until it closes the connection to the broker (AMQP server). When that connection is closed (e.g. because the worker was stopped) the tasks will be re-sent by the broker to the next available worker (or the same worker when it has been restarted), so to properly purge the queue of waiting tasks you have to stop all the workers, and then purge the tasks using celery.control.purge().

So to purge the entire queue workers must be stopped.