sub mem {
    my $mem = `tasklist /nh /fi "PID eq $$"`;
    $mem =~ tr[ \t\n][   ]s;
    return "$mem : $_[0]";
}

print mem '1';;
 perl.exe 51704 Console 1 11,296 K  : 1

$a[ $_ ] = $_ for 1  .. 1e6;;

print mem '2';;
 perl.exe 51704 Console 1 43,684 K  : 2

undef @a;;

print mem '3';;
 perl.exe 51704 Console 1 35,468 K  : 3