Memory allocation is a fairly complicated subject, and I'm not sure what Devel::Size does exactly. Moreover, I am really not a specialist on these things, so what I will say next is not at all from any insider knowledge on how Perl (and the underlying C functions) allocate memory, but from what I have read from people knowing these things presumably much better than I do. So, take it with a pinch of salt, I may be misunderstanding some of these things.

In general, I would not expect the overall memory footprint to decrease when you delete some data structures. Even if some memory has been freed, it will probably not show in these stats (due, among other things, to memory fragmentation). But if you have freed some of it by deleting some hash entries, then there is good chance that your program will be able to reuse the freed memory, so that creating a new hash entry will not increase the overall memory usage.

Update: Fixed wrong link for the Devel::Size module.

In reply to Re^5: Memory utilization and hashes by Laurent_R
in thread Memory utilization and hashes by bfdi533

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.