Re: [Numpy-discussion] Strange and hard to reproduce crash

[Lisandro D. <da...@gm...>]

On 10/30/06, Fernando Perez <fpe...@gm...> wrote:
> On 10/30/06, Charles R Harris <cha...@gm...> wrote:
>
> >  I suspect the real problem is that the refcount keeps going up. Even i=
f it
> > was unsigned it would eventually wrap to zero and with a bit of luck ge=
t
> > garbage collected. So probably something isn't decrementing the refcoun=
t.
>
> Oops, my bad: I meant *unsigned long long*, so that the refcount is a
> 64-bit object.  By the time it wraps around, you'll have run out of
> memory long ago.  Having 32 bit ref counters can potentially mean you
> run out of the counter before you run out of RAM on a system with
> sufficient memory.
>
> Cheers,

FYI, this is what is defined in Include/object.h

/* PyObject_HEAD defines the initial segment of every PyObject. */
#define PyObject_HEAD=09=09=09\
=09_PyObject_HEAD_EXTRA=09=09\
=09Py_ssize_t ob_refcnt;=09=09\
=09struct _typeobject *ob_type;

#define Py_INCREF(op) (=09=09=09=09\
=09_Py_INC_REFTOTAL  _Py_REF_DEBUG_COMMA=09\
=09(op)->ob_refcnt++)

#define Py_DECREF(op)=09=09=09=09=09\
=09if (_Py_DEC_REFTOTAL  _Py_REF_DEBUG_COMMA=09\
=09    --(op)->ob_refcnt !=3D 0)=09=09=09\
=09=09_Py_CHECK_REFCNT(op)=09=09=09\
=09else=09=09=09=09=09=09\
=09=09_Py_Dealloc((PyObject *)(op))

And '_Py_CHECK_REFCNT' macro will finally call Py_FatalError

'ob_refcnt' is a  Py_ssize_t integer, so I think you will not be able
to overflow it, unless in case of C code with refcounting bugs. Am I
right?


--=20
Lisandro Dalc=EDn
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