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SF patch #947476: Apply freelist technique to lists

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Re-use list object bodies.  Saves calls to malloc() and free() for
faster list instantiation and deallocation.
This commit is contained in:
Raymond Hettinger 2004-05-05 05:37:53 +00:00
parent 8aa8c84d18
commit 0468e416c1
2 changed files with 20 additions and 4 deletions
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21
Objects/listobject.c
View file

@ -49,6 +49,11 @@ list_resize(PyListObject *self, int newsize)
return 0;
}
/* Empty list reuse scheme to save calls to malloc and free */
#define MAXFREELISTS 80
static PyListObject *free_lists[MAXFREELISTS];
static int num_free_lists = 0;
PyObject *
PyList_New(int size)
{
@ -63,9 +68,14 @@ PyList_New(int size)
if (nbytes / sizeof(PyObject *) != (size_t)size) {
return PyErr_NoMemory();
}
op = PyObject_GC_New(PyListObject, &PyList_Type);
if (op == NULL) {
return NULL;
if (num_free_lists) {
num_free_lists--;
op = free_lists[num_free_lists];
_Py_NewReference((PyObject *)op);
} else {
op = PyObject_GC_New(PyListObject, &PyList_Type);
if (op == NULL)
return NULL;
}
if (size <= 0) {
op->ob_item = NULL;
@ -233,7 +243,10 @@ list_dealloc(PyListObject *op)
}
PyMem_FREE(op->ob_item);
}
op->ob_type->tp_free((PyObject *)op);
if (num_free_lists < MAXFREELISTS && PyList_CheckExact(op))
free_lists[num_free_lists++] = op;
else
op->ob_type->tp_free((PyObject *)op);
Py_TRASHCAN_SAFE_END(op)
}