Note that this code takes about 30-40 seconds to run to completion. Your output should match this output in the following sense: all entries in red should appear in the same order here as in your output. All entries in gray should appear, but if they appear in a different order in your output, that's ok. (This means that the gray entries' order depends on scheduling policies and timing coincedences that you don't control.)


bash$ ./threadpool_test 
**main** dispatch 3
**main** dispatch 6
  in dispatch 3
**main** dispatch 7
  in dispatch 6
  done dispatch 3
**main** done first
  in dispatch 7
  done dispatch 6
  done dispatch 7


**main** dispatch 3
**main** dispatch 6
**main** dispatch 7
  in dispatch 6
  in dispatch 3
  done dispatch 3
**main done second
  in dispatch 7
  done dispatch 6
  done dispatch 7
bash$