title: How to assure the same job doesn't run twice at the same time?
body: <p>I have a simple sidekiq job that I've set to run every 5 minutes using clockwork. What I'm worried about is that, if the job takes longer than 5 minutes, it will run again, which could cause some issues if it's running at the same time as the original job.</p>
  
  <p>Is there a way to lock the clockwork so that it only runs if the previous running has completed?</p>