Driver code is supposed to work correctly irrespective of {HEAD ~ the number} of {TAIL ~ threads} executing it 
Driver code is supposed to work correctly irrespective of { HEAD ~ the number } of { TAIL ~ threads } executing it
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH