title: Gearman callback with nested jobs
body: <p>I have a gearman job that runs and itself executes more jobs when in turn may execute more jobs. I would like some kind of callback when all nested jobs have completed. I can easily do this, but my implementations would tie up workers (spin until children are complete) which I do not want to do.</p>
  
  <p>Is there a workaround? There is no concept of "groups" in Gearman AFAIK, so I can't add jobs to a group and have something fire once that group has completed.</p>