[Python-checkins] bpo-32422: Reduce lru_cache memory usage (GH-5008)

Mon Dec 25 12:03:27 EST 2017

https://github.com/python/cpython/commit/3070b71e5eedf62e49b8e7dedab75742a5f67ece
commit: 3070b71e5eedf62e49b8e7dedab75742a5f67ece
branch: master
author: INADA Naoki <methane at users.noreply.github.com>
committer: GitHub <noreply at github.com>
date: 2017年12月26日T02:03:24+09:00
summary:
bpo-32422: Reduce lru_cache memory usage (GH-5008)
files:
A Misc/NEWS.d/next/Library/2017-12-25-20-22-47.bpo-32422.5H3Wq2.rst
M Modules/_functoolsmodule.c

diff --git a/Misc/NEWS.d/next/Library/2017-12-25-20-22-47.bpo-32422.5H3Wq2.rst b/Misc/NEWS.d/next/Library/2017-12-25-20-22-47.bpo-32422.5H3Wq2.rst
new file mode 100644
index 00000000000..5918c322237
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2017-12-25-20-22-47.bpo-32422.5H3Wq2.rst
@@ -0,0 +1,2 @@
+``functools.lru_cache`` uses less memory (3 words for each cached key) and
+takes about 1/3 time for cyclic GC.
diff --git a/Modules/_functoolsmodule.c b/Modules/_functoolsmodule.c
index a571045bcc7..ff4172d663b 100644
--- a/Modules/_functoolsmodule.c
+++ b/Modules/_functoolsmodule.c
@@ -677,26 +677,9 @@ typedef struct lru_list_elem {
 static void
 lru_list_elem_dealloc(lru_list_elem *link)
 {
- _PyObject_GC_UNTRACK(link);
 Py_XDECREF(link->key);
 Py_XDECREF(link->result);
- PyObject_GC_Del(link);
-}
-
-static int
-lru_list_elem_traverse(lru_list_elem *link, visitproc visit, void *arg)
-{
- Py_VISIT(link->key);
- Py_VISIT(link->result);
- return 0;
-}
-
-static int
-lru_list_elem_clear(lru_list_elem *link)
-{
- Py_CLEAR(link->key);
- Py_CLEAR(link->result);
- return 0;
+ PyObject_Del(link);
 }
 
 static PyTypeObject lru_list_elem_type = {
@@ -720,10 +703,7 @@ static PyTypeObject lru_list_elem_type = {
 0, /* tp_getattro */
 0, /* tp_setattro */
 0, /* tp_as_buffer */
- Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
- 0, /* tp_doc */
- (traverseproc)lru_list_elem_traverse, /* tp_traverse */
- (inquiry)lru_list_elem_clear, /* tp_clear */
+ Py_TPFLAGS_DEFAULT, /* tp_flags */
 };
 
 
@@ -959,8 +939,8 @@ bounded_lru_cache_wrapper(lru_cache_object *self, PyObject *args, PyObject *kwds
 }
 } else {
 /* Put result in a new link at the front of the queue. */
- link = (lru_list_elem *)PyObject_GC_New(lru_list_elem,
- &lru_list_elem_type);
+ link = (lru_list_elem *)PyObject_New(lru_list_elem,
+ &lru_list_elem_type);
 if (link == NULL) {
 Py_DECREF(key);
 Py_DECREF(result);
@@ -970,7 +950,6 @@ bounded_lru_cache_wrapper(lru_cache_object *self, PyObject *args, PyObject *kwds
 link->hash = hash;
 link->key = key;
 link->result = result;
- _PyObject_GC_TRACK(link);
 if (_PyDict_SetItem_KnownHash(self->cache, key, (PyObject *)link,
 hash) < 0) {
 Py_DECREF(link);
@@ -1151,7 +1130,8 @@ lru_cache_tp_traverse(lru_cache_object *self, visitproc visit, void *arg)
 lru_list_elem *link = self->root.next;
 while (link != &self->root) {
 lru_list_elem *next = link->next;
- Py_VISIT(link);
+ Py_VISIT(link->key);
+ Py_VISIT(link->result);
 link = next;
 }
 Py_VISIT(self->maxsize_O);
