Whenever I called my function, memory usage is increased around +10M per call, so I think there is some memory leak here.
....
PyObject *pair = PyTuple_New(2), *item = PyList_New(0);
PyTuple_SetItem(pair, 0, PyInt_FromLong(v[j]));
if(v[j] != DISTANCE_MAX && (p[j] || d[0][j])){
jp=j;
while(jp!=istart) {
PyList_Append(item, PyInt_FromLong(jp));
jp=p[jp];
}
PyList_Append(item, PyInt_FromLong(jp));
PyList_Reverse(item);
}
PyTuple_SetItem(pair, 1, item);
return pair;
....
When I read document, some calls like
void
bug(PyObject *list)
{
PyObject *item = PyList_GetItem(list, 0);
PyList_SetItem(list, 1, PyInt_FromLong(0L));
PyObject_Print(item, stdout, 0); /* BUG! */
}
need to put reference counts like this
void
no_bug(PyObject *list)
{
PyObject *item = PyList_GetItem(list, 0);
Py_INCREF(item);
PyList_SetItem(list, 1, PyInt_FromLong(0L));
PyObject_Print(item, stdout, 0);
Py_DECREF(item);
}
So, Where should I put Py_INCREF and Py_DECREF on my function?
The objects you create with PyInt_FromLong() and you add to the list should be kept in a local variable.
The reason are the ownership rules: PyInt_FromLong() generates a reference that you own. In the call to PyTuple_SetItem(), you lose this ownership again, because PyTuple_SetItem() "steals" it from you, so you don't have to care about. But PyList_Append() doesn't do so, it increases the refcount. In order to have the object GC'ed correctly, you have to release your ownership by DECREF'ing.
So, instead of PyList_Append(item, PyInt_FromLong(jp)), you do the following:
PyObject * jpo = PyInt_FromLong(jp);
// do some error checking here
PyList_Append(item, jpo);
Py_DECREF(jpo);
This will make the program do the right thing.
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