in reply to Re^4: Segfault on second (identical) call to a sub
in thread Segfault on second (identical) call to a sub

My fear is, that as I have now built all those packages in conjunction with 5.8.7, whatever malady is the root cause of the segfault may now be compiled into, (via errors in the Perl header files?), all the (XS components of) packages that I built in conjunction with it.

I think that fear is misplaced - I think it would be a rare case that a perl extension will need to be re-compiled (or benefit in any way from re-compiling) when you switch to perl 5.8.8.

Anyway, time will tell .... :-)

The error can still arise in perl 5.8.8. If you have a compiler, and Inline::C installed, and you run the Object Oriented Inline example from Inline's C-Cookbook.pod, you should get the "Free to wrong pool ..." error on Windows. That error still persists with perl 5.8.8 - but that's because it's the code in the Cookbook example that's in need of correction.

Cheers,
Rob
  • Comment on Re^5: Segfault on second (identical) call to a sub

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Re^6: Segfault on second (identical) call to a sub
by BrowserUk (Patriarch) on Feb 05, 2006 at 14:38 UTC

    5.8.8 certainly cures the problem with my cut down code above, but not with the code from which it is derived :(

    Now to go through the process of reducing it all over again.

    Update:

    If you get a moment, could you try wrapping the sub call in the OP code in a loop and calling say 10 times under 5.8.8? From what I am seeing, it appears that 5.8.8 allows me to call it twice without failure, but goes belly up after 4 or 5 times.

    The cuprit appears to be something in GD, but a quick scan of GD.xs shows none of the bad things demo'd in in the OO Inline C example. It use Safemalloc/Safefree exclusively and make no calls to str(n)dup(), or any of the other dodgey crt string functions.

    I tried upgrading GD to 2.30. It builds clean(ish), but segfaults when running it's testsuite. (And yes. I made sure I had the latest version of gdlib: v2.0.33 :)

    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
      Yeah ..... bummer !!
      I'm building against a pre-compiled GD library I got from somewhere. It's recent, but I don't know what version it is and couldn't find a quick way of determining the version. GD-2.30 builds cleanly against it for me (using MinGW compiler) and the tests run fine - except for one warning:

      "t/Polyline....Subroutine scale redefined at D:\comp58_M\GD-2.30\blib\lib/GD/Polyline.pm line 52."

      The error in your test script arises when 'my $raw = $gd->gd;' is called. That calls the XS function gdgd(), which can produce the "Free to wrong pool..." error on subsequent iterations.
      At first I thought it might be the gdFree() that gdgd() calls, but the fault occurs after that - ie, I guess, when gdgd() exits/returns. There's not a lot of code in gdgd() so I fiddled about with it for quite some time but couldn't get anywhere .... which means I'm about stumped. I did get some mileage from allocating with New() ... but success seemed to depend upon the strategic placement of debug printf() statements ... which is not a good sign :-)

      Cheers,
      Rob
[reply]

        I'm currently using the pre-compiled bgd.dll (v2.0.33) from boutell.com and GD.pm v2.28 that I compiled myself (with 5.8.7) without problems. Attempting to build GD.pm 2.30 against the same version bgd.lib & 5.8.8 compiles okay but traps in it's test suite, but from the results I get from tracing acid06's version of the problem, I suspect that the trap is down to perl rather than GD.

        I was about to quote the "something rotten" bit from Hamlet, but realised that timing is not good.

        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]

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