bpo-30040: new empty dict uses key-sharing dict (GH-1080)
Sizeof new empty dict becomes 72 bytes from 240 bytes (amd64).
It is same size to empty dict created by dict.clear().
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index 83cadda..108c612 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -691,10 +691,8 @@
PyObject *
PyDict_New(void)
{
- PyDictKeysObject *keys = new_keys_object(PyDict_MINSIZE);
- if (keys == NULL)
- return NULL;
- return new_dict(keys, NULL);
+ dictkeys_incref(Py_EMPTY_KEYS);
+ return new_dict(Py_EMPTY_KEYS, empty_values);
}
/* Search index of hash table from offset of entry table */
@@ -1276,6 +1274,9 @@
Py_ssize_t newsize;
PyDictKeysObject *new_keys;
+ if (minused == 0) {
+ return PyDict_New();
+ }
/* There are no strict guarantee that returned dict can contain minused
* items without resize. So we create medium size dict instead of very
* large dict or MemoryError.