title: How to control sidekiq queues concurrency
body: <p>Assuming I have  5 workers <code>A</code> , <code>B</code> , <code>C</code> , <code>D</code> , <code>E</code>. The first 3 worker belongs to <code>safe</code> queue and last two worker belongs <code>unsafe</code> queue.  The <code>unsafe</code> queue worker shouldn't run parallely and <code>safe</code> worker queue can run parallely. And, yes  two queues can run parallely. </p>
  
  <p>How do i configure this ?</p>