Python C API String Memory Consumption

MRAB google at mrabarnett.plus.com
Tue Apr 7 13:19:29 CEST 2009


k3xji wrote:
> Interestaing I changed malloc()/free() usage with PyMem_xx APIs and
> the problem resolved. However, I really cannot understand why the
> first version does not work. Here is the latest code that has no
> problems at all:
> 
> static PyObject *
> penc(PyObject *self, PyObject *args)
> {
> 	PyObject * result = NULL;
> 	unsigned char *s= NULL;
> 	unsigned char *buf = NULL;
> 	unsigned int v,len,i = 0;
> 
> 	if (!PyArg_ParseTuple(args, "s#", &s, &len))
>         return NULL;
> 
> 	buf = (unsigned char *) PyMem_Malloc(len);
> 	if (buf == NULL) {
> 		PyErr_NoMemory();
> 		return NULL;
> 	}
> 
>         /* string manipulation. */
> 
> 	result = PyString_FromStringAndSize((char *)buf, len);
> 	PyMem_Free(buf);
> 	return result;
> }
> 
In general I'd say don't mix your memory allocators. I don't know
whether CPython implements PyMem_Malloc using malloc, but it's better to
stick with CPython's memory allocators when writing for CPython.



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