I've seen this done 
my $before = current_memory();
my $after = current_memory();

SomethingSomething();

print join "\n",
'    Before  ', format_memory($before),
'    After   ', format_memory($after),
'    Diff    ', format_memory($after - $before),
    ''
    ;


sub format_memory {
    my ($self, $memory) = @_;
    1 while $memory =~ s/^([-+]?\d+)(\d{3})/$1,$2/;
    return "$memory KB";
}

sub current_memory {
    my $self = shift;
    my $out  = `ps -o rss= -p $$`;
    $out =~ s/^\s*|\s*$//gs;
    $out;
}

[download]

In reply to Re: Is there a way(maybe tool?) to know the amount of memory an array takes? by Anonymous Monk
in thread Is there a way(maybe tool?) to know the amount of memory an array takes? by PerlOnTheWay

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.