[Python-checkins] python/dist/src/Objects listobject.c,2.222,2.223
rhettinger at users.sourceforge.net
rhettinger at users.sourceforge.net
Sun Sep 12 21:53:09 CEST 2004
Update of /cvsroot/python/python/dist/src/Objects
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv20608
Modified Files:
listobject.c
Log Message:
SF #1022910: Conserve memory with list.pop()
The list resizing scheme only downsized when more than 16 elements were
removed in a single step: del a[100:120]. As a result, the list would
never shrink when popping elements off one at a time.
This patch makes it shrink whenever more than half of the space is unused.
Also, at Tim's suggestion, renamed _new_size to new_allocated. This makes
the code easier to understand.
Index: listobject.c
===================================================================
RCS file: /cvsroot/python/python/dist/src/Objects/listobject.c,v
retrieving revision 2.222
retrieving revision 2.223
diff -u -d -r2.222 -r2.223
--- listobject.c 10 Sep 2004 12:59:54 -0000 2.222
+++ listobject.c 12 Sep 2004 19:53:07 -0000 2.223
@@ -25,13 +25,14 @@
list_resize(PyListObject *self, int newsize)
{
PyObject **items;
- size_t _new_size;
+ size_t new_allocated;
+ int allocated = self->allocated;
/* Bypass realloc() when a previous overallocation is large enough
- to accommodate the newsize. If the newsize is 16 smaller than the
- current size, then proceed with the realloc() to shrink the list.
+ to accommodate the newsize. If the newsize falls lower than half
+ the allocated size, then proceed with the realloc() to shrink the list.
*/
- if (self->allocated >= newsize && self->ob_size < newsize + 16) {
+ if (allocated >= newsize && newsize >= (allocated >> 1)) {
assert(self->ob_item != NULL || newsize == 0);
self->ob_size = newsize;
return 0;
@@ -44,10 +45,12 @@
* system realloc().
* The growth pattern is: 0, 4, 8, 16, 25, 35, 46, 58, 72, 88, ...
*/
- _new_size = (newsize >> 3) + (self->ob_size < 8 ? 3 : 6) + newsize;
+ new_allocated = (newsize >> 3) + (newsize < 9 ? 3 : 6) + newsize;
+ if (newsize == 0)
+ new_allocated = 0;
items = self->ob_item;
- if (_new_size <= ((~(size_t)0) / sizeof(PyObject *)))
- PyMem_RESIZE(items, PyObject *, _new_size);
+ if (new_allocated <= ((~(size_t)0) / sizeof(PyObject *)))
+ PyMem_RESIZE(items, PyObject *, new_allocated);
else
items = NULL;
if (items == NULL) {
@@ -56,7 +59,7 @@
}
self->ob_item = items;
self->ob_size = newsize;
- self->allocated = _new_size;
+ self->allocated = new_allocated;
return 0;
}
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