I've tried it with 5.18.1 on Debian testing and I got a run that looked like this: 
2014/05/19-15:32:58 Server closing!
======= BEGIN DESTROY:16356========
============ END DESTROY:16356========
======= BEGIN DESTROY:16355========
============ END DESTROY:16355========
======= BEGIN DESTROY:16356========
============ END DESTROY:16356========

[download]
So everything is balanced nicely but the destructor for 16366 ran twice.

Could it be that the parent forks, child exits parent forks again, second child gets the same pid than the previously exited child?

So that the identical pids actually refer to different processes? But afik pids simply increase before they wrap around so that should not be possible.

In reply to Re^4: Is this absurd, or have I not RTFM? by morgon
in thread Is this absurd, or have I not RTFM? by petermogensen

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.