PID TTY      STAT   TIME  MAJFL   TRS   DRS  RSS %MEM COMMAND
22842 pts/1    R+     0:00      0    10  6941 1680  0.1 perl xxx.pl
create all the hashes
  PID TTY      STAT   TIME  MAJFL   TRS   DRS  RSS %MEM COMMAND
22842 pts/1    S+     0:23      2    10 932137 883884 85.5 perl xxx.pl
clean out hashes
  PID TTY      STAT   TIME  MAJFL   TRS   DRS  RSS %MEM COMMAND
22842 pts/1    R+     0:30     31    10 932137 885632 85.6 perl xxx.pl
we're done