[egenix-users] seg fault on import mx.DateTime Python2.3.3 egenix-base-2.0.5

[Jacob Smullyan]

Hello --

To provide some more (circumstantial) evidence that there is a real
bug associated with MXDATETIME_FREELIST:

For some time I've been trying to figure out why skunkweb dumps core
on Python 2.3.x on Linux x86 (about one in a thousand requests in
typical use). The core files showed an attempt to free an invalid
pointer, but I could find the smoking gun that tied it to any
particular module.  (Alas, I don't know enough to debug this very
well.)  By process of elimination, however, I think I've found that
the culprit was mx.DateTime (in either 2.0.5 or 2.1.0 incarnations);
after rewriting skunkweb so it could run without it, the segfault went
away.  Furthermore, the tests I am running right now suggest that
undefing MXDATETIME_FREELIST seems to solve the problem.  I'll perform
more testing and report back if this is a red herring, but at this
point that would be statistically unlikely.

Incidentally, I've tested with different compilers (gcc 2.95.3,
3.2.3), different 2.3 releases, different configure and CFLAGS, etc.,
and the bug is reproducible across the board.  

I can provide core files, backtraces, etc., upon request.

Cheers,

Jacob Smullyan

On Fri, Feb 06, 2004 at 04:16:58PM -0800, Ross Brattain wrote:
> "M.-A. Lemburg" <mal at egenix.com> writes:
> 
> > Are you using a Python version that's compiled with debug
> > mode enabled (or have you used such a Python version to
> > compile mxDateTime) ?
> > 
> 
> No, just vanilla ./configure.
> 
> I rebuilt Python 2.2.3 / egenix-base-2.0.4 and had the same problem.
> 
> Because of this line from the backtrace:
> #0  mxDateTime_FromDateAndTime (year=1, month=1, day=1, hour=1, minute=1, second=0) at mx/DateTime/mxDateTime/mxDateTime.c:333
> 
> mxDateTime.c:333 :
> 
> #ifdef MXDATETIME_FREELIST
>     if (mxDateTime_FreeList) {
> 	datetime = mxDateTime_FreeList;
> 	mxDateTime_FreeList = *(mxDateTimeObject **)mxDateTime_FreeList;
> 	datetime->ob_type = &mxDateTime_Type;
> ->	_Py_NewReference(datetime);
>     }
>     else
> #endif 
> 	 {
> 	datetime = PyObject_NEW(mxDateTimeObject,&mxDateTime_Type);
> 	if (datetime == NULL)
> 	    return NULL;
>     }
> 
> I undefed MXDATETIME_FREELIST and rebuilt and everything seems fine.
> 
> --- egenix-mx-base-2.0.5/mx/DateTime/mxDateTime/mxDateTime.c    2001-12-10 02:15:49.000000000 -0800
> +++ egenix-mx-base-2.0.5-mod/mx/DateTime/mxDateTime/mxDateTime.c        2004-02-05 22:54:07.000000000 -0800
> @@ -76,7 +76,7 @@
>  #define STRFTIME_OUTPUT_SIZE   1024
>  
>  /* Define these to have the module use free lists (saves malloc calls) */
> -#define MXDATETIME_FREELIST
> +#undef MXDATETIME_FREELIST
>  #define MXDATETIMEDELTA_FREELIST
>  
>  /* Define this to enable the copy-protocol (__copy__, __deepcopy__) */
> 
> 
> This is not the root cause because, as mentioned, a rebuild of 
> Python 2.2.3 / egenix-base-2.0.4 on this machine exhibited the same
> problem.
> 
> My working production environment (different machine) is:
> Python 2.2.3 (#1, Jun  5 2003, 13:06:29) 
> [GCC 3.2.3 20030415 (Debian prerelease)] on linux2
> 
> and egenix-base-2.0.4
> 
> I rebuilt Python-2.2.3 / egenix-base-2.0.4 on production and it still
> works.
> 
> So is it a gcc problem?
> 
> -Ross B.
> 
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