[Numpy-discussion] segfaults when passing ndarray subclass to ufunc with out=None
Darren Dale
dsdale24@gmail....
Sun Mar 8 09:18:24 CDT 2009
On Sun, Feb 8, 2009 at 12:49 PM, Darren Dale <dsdale24@gmail.com> wrote:
> I am seeing some really strange behavior when I try to pass an ndarray
> subclass and out=None to numpy's ufuncs. This example will reproduce the
> problem with svn numpy, the first print statement yields 1 as expected, the
> second yields "<type 'builtin_function_or_method'>" and the third yields a
> segmentation fault:
>
> import numpy as np
>
> class MyArray(np.ndarray):
>
> __array_priority__ = 20
>
> def __new__(cls):
> return np.asarray(1).view(cls).copy()
>
> def __repr__(self):
> return 'my_array'
>
> __str__ = __repr__
>
> def __mul__(self, other):
> return super(MyArray, self).__mul__(other)
>
> def __rmul__(self, other):
> return super(MyArray, self).__rmul__(other)
>
> mine = MyArray()
> print np.multiply(1, 1, None)
> x = np.multiply(mine, mine, None)
> print type(x)
> print x
>
I think I might have found a fix for this. The following patch allows my
script to run without a segfault:
$ svn diff
Index: umath_ufunc_object.inc
===================================================================
--- umath_ufunc_object.inc (revision 6566)
+++ umath_ufunc_object.inc (working copy)
@@ -3212,13 +3212,10 @@
output_wrap[i] = wrap;
if (j < nargs) {
obj = PyTuple_GET_ITEM(args, j);
- if (obj == Py_None) {
- continue;
- }
if (PyArray_CheckExact(obj)) {
output_wrap[i] = Py_None;
}
- else {
+ else if (obj != Py_None) {
PyObject *owrap =
PyObject_GetAttrString(obj,"__array_wrap__");
incref = 0;
if (!(owrap) || !(PyCallable_Check(owrap))) {
That call to continue skipped this bit of code in the loop, which is
apparently important:
if (incref) {
Py_XINCREF(output_wrap[i]);
}
I've tested the trunk on 64 bit linux, with and without this patch applied,
and I get the same result in both cases: 1 known failure, 11 skips. Is there
any chance someone could consider applying this patch before 1.3 ships?
Darren
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