title: delayed_job process same named queue on multiple workers one job at a time
body: <p>I have different objects.</p>
  
  <pre><code>A  B  C
  </code></pre>
  
  <p>Each object has different jobs to process.</p>
  
  <pre><code>A  B  C
  1  1  1
  2  2  2
  3  3  3
  </code></pre>
  
  <p>I got multiple delayed_job workers processing my jobs. I don't want to assign queues to them, so every worker can process jobs for every object, as there is no rule when which object will start a job.</p>
  
  <p>So the queue can look like this</p>
  
  <pre><code>A3 B2 C3 C1 C2 A2 A1 B3
  </code></pre>
  
  <p>Any job of any object can be added to the queue at any time and can be processed by any worker, but, because of the objects characteristics there can only be one active job from any object at the same time.</p>
  
  <p>Is this possible with delayed job?</p>