I was playing around with top to monitor a program for memory size, and noticed that the output of top (for size) dosn't match the output of Proc::ProcessTable. Anyone know the explanation? Run the 2 sample scripts on the same process.

#!/usr/bin/perl
use warnings;
use strict;
use IPC::Open3;
use Tk;

my $pid = shift;
my $pid1 = open3(0, \*READ,0,"top -d 1 -b -p $pid ");
waitpid($pid1, 1);
my $sizeold = 0;

my $mw = new MainWindow;
$mw->overrideredirect(1);
my $t = $mw->Text(-width=>25, -height=>1, -bg=>'black',-fg=>'yellow')-
+>pack;

my $id = Tk::After->new($mw,50,'repeat',\&refresh);

MainLoop;

sub refresh{
  my @words = split(/\s+/,<READ>);
  $words[0] ||= 0;
  if($words[0] =~ /$pid/){
              $t->delete('1.0','end');
              $t->insert('end',"PID: $pid ->  $words[4]");
              if($words[4] != $sizeold){print chr(07)}
              $sizeold = $words[4];
              }
}
[download]

###########################################################

#!/usr/bin/perl
use warnings;
use strict;
use Tk;
use Proc::ProcessTable;
#Dosn't give same size as top ? 


my $sizeold = 0;
my $pid = shift;
my $t = new Proc::ProcessTable;
my $p;

foreach my $p1 (@{$t->table}){
    if($p1->pid =~ /$pid/){ $p = $p1 }
}

my $mw = new MainWindow;
$mw->overrideredirect(1);
my $text = $mw->Text(-width=>25, -height=>1, -bg=>'black',-fg=>'yellow
+')->pack;

my $id = Tk::After->new($mw,50,'repeat',\&refresh);

MainLoop;

sub refresh{
       $text->delete('1.0','end');
       my $insert= 'PID: '.$p->pid.' -> '.$p->size;
       $text->insert('end',$insert);
              if($p->size != $sizeold){print chr(07)}
      $sizeold = $p->size;
#      print $p->pid,"  ",$p->cmndline,"  ",$p->size,"\n"; 
    }
[download]