$ perl test_read.pl
  time    vsz (  diff)    rss (  diff) shared (  diff)   code (  diff)   data (  diff) 
     0  78300 ( 78300)   2116 (  2116)   1412 (  1412)     12 (    12)   1164 (  1164) Begin 
    17  6461328 ( 6383028)  6296400 ( 6294284)   1428 (    16)     12 (     0)  6384192 ( 6383028) After file read