[Numpy-discussion] Re: ANN: numarray-1.2.3 -- segfault in in my C program

[Todd Miller]

On Mon, 2005-05-09 at 17:58 -0700, Sebastian Haase wrote:
> Hi,
> Now I'm back to this problem. In the meantime I upgraded again:
> >>> na.__version__
> '1.4.0'
> All my python2.2 + numarray + my-extensions work. (Debian Woody)
> Only my C++ program segfaults. It looked to me like a problem with 
> NA_NewAllFromBuffer -- was there any recent change ?

Yes there was.  You can undo it in your private CVS checkout like this:

% cd numarray/Src
% cvs update -j 1.3 -1.2 libnumarray.ch
% cd ..
% python setup.py install --genapi --selftest

> (I saw that I was using a bytestride of 0 - but it used to work and giving a 1 
> for that argument still segfaults  -- is 0 OK ??)

I don't know for sure.  It seems like it should be... just leads to 0
strides.

> Now I noticed in the gdb traceback that I chokes is the function
> deferred_libnumarray_init
> ((
> ((#0  0x406d68d5 in PyObject_GetAttrString () from
> ((/usr/lib/libpython2.2.so.0.0 #1  0x410f905e in
> ((deferred_libnumarray_init () at Src/libnumarraymodule.c:149
> 
> Is this function the standard function that always get called to init numarray 
> (in embedded Python AND using "normal" python) ?

Yes and no.  deferred_libnumarray_init() is really for stuff that can't
be done at libnumarray.so init time.  This is because of circular
dependencies.

The "real" numarray init function is either "import numarray" in Python
or "import_array()" in C.  After that,  certain calls into the C-API
trigger the deferred initialization.  deferred_libnumarray_init() is
never called directly by application code.

> Have you tested this with Python2.2 ?

Yes, using the numarray unit tests.  NewAllFromBuffer is also used
directly by the numarray ufuncs,  so it is tested to a degree by
numarray itself.  My gut feel is you're hitting an embedding problem,
but my gut is only so accurate.

> 
> (See for more info  below == I did follow Todd's suggestions 1 & 2, but hope 
> not having to recompile python from source.)

That's really not hard.   A 5-10 minute exercise usually.  

Regards,
Todd