On Mon, Oct 5, 2009 at 9:25 PM, Ondrej Certik <ond...@certik.cz> wrote: > On Mon, Oct 5, 2009 at 8:38 PM, Ondrej Certik <ond...@certik.cz> wrote: >> On Mon, Oct 5, 2009 at 7:34 PM, Charles R Harris >> <charlesr.har...@gmail.com> wrote: >>> >>> >>> On Mon, Oct 5, 2009 at 7:40 PM, Ondrej Certik <ond...@certik.cz> wrote: >> [...] >>>> still alive >>>> Segmentation fault >>>> >>>> >>>> >>>> What puzzles me is that there is no debugging print statement just >>>> before the segfault. >>> >>> Maybe you need to flush the buffer. That is a good thing to do when >>> segfaults are about. >> >> I tried to put "fflush(NULL);" after it, but it didn't help. I have >> created a super simple demo for anyone to play: >> >> >> $ git clone git://github.com/certik/segfault.git >> $ cd segfault/ >> $ vim Makefile # <-- edit the python and numpy include paths >> $ make >> $ python test.py >> I am still alive >> Segmentation fault >> >> where test.py is: >> >> $ cat test.py >> import _hermes1d >> v = _hermes1d.test() >> print v >> >> >> and _hermes1d.pyx is: >> >> $ cat _hermes1d.pyx >> def test(): >> cdef npy_intp size >> cdef ndarray newarr >> cdef double *arrsource >> >> size = 10 >> arrsource = <double *>malloc(sizeof(double) * size) >> print "I am still alive" >> newarr = PyArray_SimpleNewFromData(1, &size, NPY_DOUBLE, <void >> *>arrsource) >> print "I am dead." >> >> return newarr >> >> >> So I bet there is something very stupid that I am missing. Still >> investigating... > > I didn't call _import_array() ! > > This patch fixes it: > > > diff --git a/_hermes1d.pxd b/_hermes1d.pxd > index 9994c28..f5e8868 100644 > --- a/_hermes1d.pxd > +++ b/_hermes1d.pxd > @@ -54,6 +54,8 @@ cdef extern from "arrayobject.h": > object PyArray_SimpleNewFromData(int nd, npy_intp* dims, int typenum, > void* data) > > + void _import_array() > + > cdef extern from "Python.h": > ctypedef void PyObject > void Py_INCREF(PyObject *x) > diff --git a/_hermes1d.pyx b/_hermes1d.pyx > index e542ddc..7a4beec 100644 > --- a/_hermes1d.pyx > +++ b/_hermes1d.pyx > @@ -2,6 +2,7 @@ def test(): > cdef npy_intp size > cdef ndarray newarr > cdef double *arrsource > + _import_array() > > size = 10 > arrsource = <double *>malloc(sizeof(double) * size) > > > > > I think I learned something today the hard way.
The only mention of the _import_array() in the documentation that I found is here: http://docs.scipy.org/doc/numpy/reference/c-api.array.html#NO_IMPORT_ARRAY but I don't understand what it means ---- do I have to just call _import_array() and then I can use numpy CAPI, or do I also have to define those PY_ARRAY_UNIQUE_SYMBOL etc? Btw, to explain my original post for future readers --- the real problem was that PyArray_Type was NULL and thus &PyArray_Type segfaulted. That happened in the definition: #define PyArray_SimpleNewFromData(nd, dims, typenum, data) \ PyArray_New(&PyArray_Type, nd, dims, typenum, NULL, \ data, 0, NPY_CARRAY, NULL) so it is *extremely* confusing, since PyArray_SimpleNewFromData() was being called from my code, but PyArray_New never started, it segfaulted in between. I think now it is clear what is going on. Only I don't understand the intention, but I can now get my job done. Ondrej _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
