https://github.com/python/cpython/commit/5a549e82b81378cb294904dab49cbee853bddd64
commit: 5a549e82b81378cb294904dab49cbee853bddd64
branch: main
author: Donghee Na <[email protected]>
committer: corona10 <[email protected]>
date: 2026-06-26T17:11:33Z
summary:
gh-152235: Defer GC tracking in set.union and set.difference (gh-152290)
files:
M
Misc/NEWS.d/next/Core_and_Builtins/2026-06-26-22-03-16.gh-issue-152235.ZKWiWk.rst
M Objects/setobject.c
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2026-06-26-22-03-16.gh-issue-152235.ZKWiWk.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2026-06-26-22-03-16.gh-issue-152235.ZKWiWk.rst
index bcc128404897da..ff89a2445cb4fe 100644
---
a/Misc/NEWS.d/next/Core_and_Builtins/2026-06-26-22-03-16.gh-issue-152235.ZKWiWk.rst
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2026-06-26-22-03-16.gh-issue-152235.ZKWiWk.rst
@@ -1,2 +1,3 @@
-Defer GC tracking of :meth:`set.intersection`, :meth:`set.difference` and
-:meth:`set.symmetric_difference`. Patch by Donghee Na.
+Defer GC tracking of :meth:`set.intersection`, :meth:`set.difference`,
+:meth:`set.symmetric_difference`, :meth:`set.union` and ``set.__sub__``.
+Patch by Donghee Na.
diff --git a/Objects/setobject.c b/Objects/setobject.c
index d8c38ff1c1d899..8fdd1eb26118c0 100644
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -1577,6 +1577,21 @@ _PySet_Freeze(PyObject *set)
return Py_NewRef(set);
}
+static PyObject *
+set_copy_untracked_lock_held(PySetObject *so)
+{
+ _Py_CRITICAL_SECTION_ASSERT_OBJECT_LOCKED(so);
+ PyObject *copy = make_new_set_basetype_untracked(Py_TYPE(so), NULL);
+ if (copy == NULL) {
+ return NULL;
+ }
+ if (set_merge_lock_held((PySetObject *)copy, (PyObject *)so) < 0) {
+ Py_DECREF(copy);
+ return NULL;
+ }
+ return copy;
+}
+
/*[clinic input]
@critical_section
set.copy
@@ -1589,14 +1604,9 @@ static PyObject *
set_copy_impl(PySetObject *so)
/*[clinic end generated code: output=c9223a1e1cc6b041 input=c169a4fbb8209257]*/
{
- _Py_CRITICAL_SECTION_ASSERT_OBJECT_LOCKED(so);
- PyObject *copy = make_new_set_basetype(Py_TYPE(so), NULL);
- if (copy == NULL) {
- return NULL;
- }
- if (set_merge_lock_held((PySetObject *)copy, (PyObject *)so) < 0) {
- Py_DECREF(copy);
- return NULL;
+ PyObject *copy = set_copy_untracked_lock_held(so);
+ if (copy != NULL) {
+ _PyObject_GC_TRACK(copy);
}
return copy;
}
@@ -1652,7 +1662,8 @@ set_union_impl(PySetObject *so, PyObject * const *others,
PyObject *other;
Py_ssize_t i;
- result = (PySetObject *)set_copy((PyObject *)so, NULL);
+ result = (PySetObject *)make_new_set_basetype_untracked(Py_TYPE(so),
+ (PyObject *)so);
if (result == NULL)
return NULL;
@@ -1665,6 +1676,7 @@ set_union_impl(PySetObject *so, PyObject * const *others,
return NULL;
}
}
+ _PyObject_GC_TRACK(result);
return (PyObject *)result;
}
@@ -2055,11 +2067,11 @@ set_difference_update_impl(PySetObject *so, PyObject *
const *others,
}
static PyObject *
-set_copy_and_difference(PySetObject *so, PyObject *other)
+set_copy_and_difference_untracked(PySetObject *so, PyObject *other)
{
PyObject *result;
- result = set_copy_impl(so);
+ result = set_copy_untracked_lock_held(so);
if (result == NULL)
return NULL;
if (set_difference_update_internal((PySetObject *) result, other) == 0)
@@ -2069,7 +2081,7 @@ set_copy_and_difference(PySetObject *so, PyObject *other)
}
static PyObject *
-set_difference(PySetObject *so, PyObject *other)
+set_difference_untracked(PySetObject *so, PyObject *other)
{
PyObject *result;
PyObject *key;
@@ -2085,13 +2097,13 @@ set_difference(PySetObject *so, PyObject *other)
other_size = PyDict_GET_SIZE(other);
}
else {
- return set_copy_and_difference(so, other);
+ return set_copy_and_difference_untracked(so, other);
}
/* If len(so) much more than len(other), it's more efficient to simply copy
* so and then iterate other looking for common elements. */
if ((PySet_GET_SIZE(so) >> 2) > other_size) {
- return set_copy_and_difference(so, other);
+ return set_copy_and_difference_untracked(so, other);
}
result = make_new_set_basetype_untracked(Py_TYPE(so), NULL);
@@ -2118,7 +2130,6 @@ set_difference(PySetObject *so, PyObject *other)
}
Py_DECREF(key);
}
- _PyObject_GC_TRACK(result);
return result;
}
@@ -2142,7 +2153,6 @@ set_difference(PySetObject *so, PyObject *other)
}
Py_DECREF(key);
}
- _PyObject_GC_TRACK(result);
return result;
}
@@ -2169,7 +2179,7 @@ set_difference_multi_impl(PySetObject *so, PyObject *
const *others,
other = others[0];
Py_BEGIN_CRITICAL_SECTION2(so, other);
- result = set_difference(so, other);
+ result = set_difference_untracked(so, other);
Py_END_CRITICAL_SECTION2();
if (result == NULL)
return NULL;
@@ -2185,6 +2195,7 @@ set_difference_multi_impl(PySetObject *so, PyObject *
const *others,
return NULL;
}
}
+ _PyObject_GC_TRACK(result);
return result;
}
@@ -2197,8 +2208,11 @@ set_sub(PyObject *self, PyObject *other)
PyObject *rv;
Py_BEGIN_CRITICAL_SECTION2(so, other);
- rv = set_difference(so, other);
+ rv = set_difference_untracked(so, other);
Py_END_CRITICAL_SECTION2();
+ if (rv != NULL) {
+ _PyObject_GC_TRACK(rv);
+ }
return rv;
}
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