title: How to prevent the same task to be executed by celery?
body: <p>I'm implementing a cache server that uses a celery task to update the cache in background. There is only one task that I call it with different arguments (cache keys).</p>
  
  <p>Since after connecting this server to my main production server it will receive tens of requests per second for the same cache key I want to make sure there are never more than one of the update tasks with the same cache key inside celery queue (working as a queue and a set at the same time).</p>
  
  <p>I thought of using a redis set to make sure of that before running the task but I'm looking for a better way.</p>