#!/usr/local/bin/perl

    use strict;
    use warnings;

    my $NAME = "";

    my ( $FB_CacheMemoryVSZ, $FB_CacheMemoryRSS ) = &Display_Mem_Usage($$,$NAME,0);
    print "Before: Virtual Memory: $FB_CacheMemoryVSZ\tReal Memory: $FB_CacheMemoryRSS\n";
    {    my %RCache;
        for my $key ( 1_000 .. 11_000 )
        {    $RCache{$key} = chr( $key % 255 ) x 2_048;
        }
        ( $FB_CacheMemoryVSZ, $FB_CacheMemoryRSS ) = &Display_Mem_Usage($$,$NAME,0);
        print "After:  Virtual Memory: $FB_CacheMemoryVSZ\tReal Memory: $FB_CacheMemoryRSS\n";
    }
    ( $FB_CacheMemoryVSZ, $FB_CacheMemoryRSS ) = &Display_Mem_Usage($$,$NAME,0);
    print "$$: Virtual Memory: $FB_CacheMemoryVSZ\tReal Memory: $FB_CacheMemoryRSS\n\n";

    my $fork = fork();
    if ( $fork )
    {
        ( $FB_CacheMemoryVSZ, $FB_CacheMemoryRSS ) = &Display_Mem_Usage($$,$NAME,0);
        print "$$: Virtual Memory: $FB_CacheMemoryVSZ\tReal Memory: $FB_CacheMemoryRSS\n\n";
    }
    else
    {    ( $FB_CacheMemoryVSZ, $FB_CacheMemoryRSS ) = &Display_Mem_Usage($$,$NAME,0);
        print "$$: Virtual Memory: $FB_CacheMemoryVSZ\tReal Memory: $FB_CacheMemoryRSS\n\n";
    }

    exit;

sub Display_Mem_Usage
{    # VSZ is size in KBytes of the virtual memory ( VSZ * 1024 )
    # RSS is size in pages of real memory ( 1024 * RSS )
    my $cpid = shift; my $name = shift; my $from = shift;
    my $var = ""; my $fh;

    my $arg = qq| -o "vsz rssize" -p $cpid|;
      open ( $fh, "-|", "/bin/ps $arg" ) or die "Display_Mem_Usage: Not open \'$arg\': $!";
    while (<$fh>)
    { $var .= $_; }
    close $fh;
    my $rno = my @ref = split(/\n/,$var); if ( $rno < 2 ) { return ( -1, -1 ); }
    my $info = join(" ", split " ", $ref[1]);
    my ($vmem,$rmem) = ( split(/\ /,$info) );
    return ( $vmem , $rmem );
 }


__END__

   AIX:#  perl ckmem.cgi    
   Before: Virtual Memory: 776     Real Memory: 852
   After:  Virtual Memory: 21904   Real Memory: 21980
   41030: Virtual Memory: 21908    Real Memory: 21984
   
   40244: Virtual Memory: 424      Real Memory: 404   ## Child
   
   41030: Virtual Memory: 21912    Real Memory: 21900
   
   AIX:# 
   
   
   Linux:# perl ckmem.cgi
   Before: Virtual Memory: 5288    Real Memory: 1928
   After:  Virtual Memory: 26136   Real Memory: 22804
   26362: Virtual Memory: 26128    Real Memory: 22804
   
   26362: Virtual Memory: 26128    Real Memory: 22808
   
   26369: Virtual Memory: 26128    Real Memory: 21600   ## Child
   
   Linux:#