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

[Sebastian Haase]

Todd,
I would be very thankful if you could compile and run this program:
<testnumarrayembedded.cpp>
#include <Python.h>
#include <numarray/libnumarray.h>
int main() {
  Py_Initialize();
  PyObject *pymodMain = PyImport_ImportModule("__main__");
  PyObject* globals   = PyModule_GetDict(pymodMain);
  PyEval_InitThreads();

//	import_libnumarray();
  PyObject *module = PyImport_ImportModule("numarray.libnumarray");     
  if (!module)                                                        
	Py_FatalError("Can't import module 'numarray.libnumarray'");    
  if (module != NULL) {                                               
	PyObject *module_dict = PyModule_GetDict(module);                 
	PyObject *c_api_object =                                          
	  PyDict_GetItemString(module_dict, "_C_API");               
	if (PyCObject_Check(c_api_object)) {                              
	  libnumarray_API = (void **)PyCObject_AsVoidPtr(c_api_object);      
	} else {                                                          
	  Py_FatalError("Can't get API for module 'numarray.libnumarray'"); 
	}                                                                 
  }
  float *colMapsRGB = new float[4 * 3 * 256];
  int shape[3]= { 4, 3, 256 };
  PyObject *obj = PyBuffer_FromReadWriteMemory(colMapsRGB, 4*3 *256 * 
sizeof(float));
  PyObject *obj2 =(PyObject*) NA_NewAllFromBuffer( 3, shape, tFloat32, obj, 
												   0, 0, NA_ByteOrder(), 1, 1/*writable*/) ;
  return 0; 
}
</testnumarrayembedded.cpp>

I compile with:
g++-2.95 -o testnumarrayembedded -Wall -finline-functions -g -I/usr/include/
python2.2 -I/jws30/haase/myCVS/numarray/Include testnumarrayembedded.cpp 
-pthread -lpython2.2


It runs through with setting PYTHONPATH to my old numarray(1.1) directory.
And now with numarray CVS it now doesn't even find the library...
$ ./testnumarrayembedded
Fatal Python error: Can't import module 'numarray.libnumarray'
Aborted

Still, my non-embedded python shell runs all fine - your CVS-update (-j...) 
suggestion didn't seem to make a difference.

Thanks,
Sebastian
 


On Tuesday 10 May 2005 05:13, Todd Miller wrote:
> 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
>
>
>
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