title: Celery check if queue is executing
body: <p>I have to spawn celery tasks, which have to have some namespace (for example user id).
  So I'm spawn it by </p>
  
  <pre><code>scrapper_start.apply_async((request.user.id,), queue=account.Account_username)
  app.control.add_consumer(account.Account_username, reply=True)
  </code></pre>
  
  <p>And tasks spawns recursively, from other task.
  Now I have to check, if tasks of queue are executing. Tried to check list length in redis, it return true number before celery start executing.
  How to solve this problem. I need only to check, if queue or consumer is executing or already empty. Thanks</p>