Yes, this makes the trick. After changing source code to 
#include <pthread.h>
 #include "EXTERN.h"
 #include "perl.h"
 #include "XSUB.h"
 #include "ppport.h"

 #undef free
 #undef malloc

[download]

You'll get away with that as long as you do not attempt to pass anything you malloc() to perl.

When it gets interesting is when you try to free() something allocated by Perl within your C/XS code; or vice versa.

As I mentioned above, under iThreads, different pools of memory are used for each (perl instantiated) thread via the custom allocator.

Attempt free something allocated by the CRT (ie. by you in your XS code with #undef malloc) and then free it using the custom allocators free() (eg. by passing it into Perl and then letting it go out of scope) and you'll probably get the infamous: "free to wrong pool" message.

Attempt to free something allocated by that allocator using the CRT free() and you'll blow up bigtime.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.

In reply to Re^9: XS: free() outside of the main thread causes crash on Windows by BrowserUk
in thread XS: free() outside of the main thread causes crash on Windows by OlegG

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.