Tuple size and memory allocation for embedded Python
craig at postnewspapers.com.au
Fri Jan 21 17:27:54 EST 2005
On Fri, 2005-01-21 at 16:03 -0600, Jinming Xu wrote:
> Hi Folks,
> Python seems unstable, when allocating big memory. For example, the
> following C++ code creates a tuple of tuples:
> PyObject* arCoord = PyTuple_New(n);
> double d = 1.5;
> for(int i=0; i<n; i++)
> PyObject* coord = PyTuple_New(2);
> PyTuple_SetItem(coord,0, PyFloat_FromDouble(d));//x
> PyTuple_SetItem(coord,1, PyFloat_FromDouble(d));//y
> PyTuple_SetItem(arCoord,i, coord);
> When the n is small, say 100, the code works fine. when n is big, say
> 10,000, Python has trouble allocating memory, saying:
> "Exception exceptions.IndexError: 'tuple index out of range' in 'garbage
> collection' ignored
> Fatal Python error: unexpected exception during garbage collection
You're not checking for errors from PyTuple_SetItem. You need to do so,
otherwise exceptions will go uncaught and may pop up at weird points
later in your software's execution, or crash things.
PyObject *p, int pos, PyObject *o)
Inserts a reference to object o at position pos of the tuple
pointed to by p. It returns 0 on success. Note: This function
``steals'' a reference to o.
It returns an int result code, so you should probably be checking it.
You CERTAINLY should be ensuring that PyTuple_New() doesn't return NULL
(meaning a failure, probably of memory allocation).
I also don't see anything in there to resize the tuple.
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