title: Celery: Task Singleton?
body: <p>I have a task that I need to run asynchronously from the web page that triggered it.  This task runs rather long, and as the web page could be getting a lot of these requests, I'd like celery to only run one instance of this task at a given time.</p>
  
  <p>Is there any way I can do this in Celery natively?  I'm tempted to create a database table that holds this state for all the tasks to communicate with, but it feels hacky. </p>