https://github.com/python/cpython/commit/998587cd74f1d34dd7759ed0c85c622e9969e711
commit: 998587cd74f1d34dd7759ed0c85c622e9969e711
branch: 3.13
author: Donghee Na <[email protected]>
committer: corona10 <[email protected]>
date: 2026-06-26T12:35:30Z
summary:
[3.13] gh-152235: Defer GC tracking of set and frozenset to end of
connstruction (gh-152272)
[3.13] gh-152235: Defer GC tracking of set and frozenset to end of construction
(gh-152237)
(cherry picked from commit 908f438e198a753d40d1166b5f8725e650a9ed6e)
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2026-06-26-05-49-13.gh-issue-152235.YU20T9.rst
M Objects/setobject.c
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2026-06-26-05-49-13.gh-issue-152235.YU20T9.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2026-06-26-05-49-13.gh-issue-152235.YU20T9.rst
new file mode 100644
index 00000000000000..8d386ad458dfff
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2026-06-26-05-49-13.gh-issue-152235.YU20T9.rst
@@ -0,0 +1,2 @@
+Defer GC tracking of a :class:`set` or :class:`frozenset` to the end of its
+construction from iterable. Patch by Donghee Na.
diff --git a/Objects/setobject.c b/Objects/setobject.c
index 0743870cec859c..e00ed6a38c9699 100644
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -1086,7 +1086,9 @@ make_new_set(PyTypeObject *type, PyObject *iterable)
assert(PyType_Check(type));
PySetObject *so;
- so = (PySetObject *)type->tp_alloc(type, 0);
+ // Allocate untracked: the fill below runs user code, and a half-built
+ // set must not be reachable from another thread via gc.get_objects().
+ so = (PySetObject *)_PyType_AllocNoTrack(type, 0);
if (so == NULL)
return NULL;
@@ -1105,6 +1107,8 @@ make_new_set(PyTypeObject *type, PyObject *iterable)
}
}
+ // Track only once fully built.
+ _PyObject_GC_TRACK(so);
return (PyObject *)so;
}
@@ -2499,7 +2503,7 @@ PyTypeObject PySet_Type = {
0, /* tp_descr_set */
0, /* tp_dictoffset */
(initproc)set_init, /* tp_init */
- PyType_GenericAlloc, /* tp_alloc */
+ _PyType_AllocNoTrack, /* tp_alloc */
set_new, /* tp_new */
PyObject_GC_Del, /* tp_free */
.tp_vectorcall = set_vectorcall,
@@ -2590,7 +2594,7 @@ PyTypeObject PyFrozenSet_Type = {
0, /* tp_descr_set */
0, /* tp_dictoffset */
0, /* tp_init */
- PyType_GenericAlloc, /* tp_alloc */
+ _PyType_AllocNoTrack, /* tp_alloc */
frozenset_new, /* tp_new */
PyObject_GC_Del, /* tp_free */
.tp_vectorcall = frozenset_vectorcall,
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