604.pl

#!/usr/bin/env perl

use strict;
use warnings;
use 5.010;

use Data::Dumper;
$Data::Dumper::Sortkeys = 1;
$Data::Dumper::Terse = 1;
$Data::Dumper::Indent = 1;
$Data::Dumper::Quotekeys = 1;
sub dmp { say &Dumper; };

=a
RESULTS:

uninitialized
size: 24
total_size: 24
after 1024**2
size: 1052712
total_size: 1052712
after $x = undef
size: 1052712
total_size: 1052712
after 1024**2
size: 1052712
total_size: 1052712
after undef ($x)
size: 40
total_size: 40

=cut

use Devel::Size qw(size total_size);
my $x;

say 'uninitialized';
say 'size: ', size ($x);
say 'total_size: ', total_size ($x);

$x = 'x'x 1024**2;
say 'after 1024**2';
say 'size: ', size ($x);
say 'total_size: ', total_size ($x);

$x = undef;

say 'after $x = undef';
say 'size: ', size ($x);
say 'total_size: ', total_size ($x);

$x = 'x'x 1024**2;
say 'after 1024**2';
say 'size: ', size ($x);
say 'total_size: ', total_size ($x);

undef ($x);
say 'after undef ($x)';
say 'size: ', size ($x);
say 'total_size: ', total_size ($x);