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GH-113462: Limit the number of versions that a single class can use. (GH-114900)

This commit is contained in:
Mark Shannon 2024-02-05 16:20:54 +00:00 committed by GitHub
parent 87cd20a567
commit 992446dd5b
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4 changed files with 22 additions and 1 deletions
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1
Include/cpython/object.h
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@ -229,6 +229,7 @@ struct _typeobject {
/* bitset of which type-watchers care about this type */
unsigned char tp_watched;
uint16_t tp_versions_used;
};
/* This struct is used by the specializer

13
Lib/test/test_type_cache.py
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@ -79,6 +79,19 @@ class TypeCacheTests(unittest.TestCase):
_clear_type_cache()
def test_per_class_limit(self):
class C:
x = 0
type_assign_version(C)
orig_version = type_get_version(C)
for i in range(1001):
C.x = i
type_assign_version(C)
new_version = type_get_version(C)
self.assertEqual(new_version, 0)
@support.cpython_only
class TypeCacheWithSpecializationTests(unittest.TestCase):

2
Misc/NEWS.d/next/Core and Builtins/2024-02-02-05-27-48.gh-issue-113462.VMml8q.rst Normal file
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@ -0,0 +1,2 @@
Limit the number of versions that a single class can use. Prevents a few
wayward classes using up all the version numbers.

7
Objects/typeobject.c
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@ -908,6 +908,8 @@ type_mro_modified(PyTypeObject *type, PyObject *bases) {
}
}
#define MAX_VERSIONS_PER_CLASS 1000
static int
assign_version_tag(PyInterpreterState *interp, PyTypeObject *type)
{
@ -922,7 +924,10 @@ assign_version_tag(PyInterpreterState *interp, PyTypeObject *type)
if (!_PyType_HasFeature(type, Py_TPFLAGS_READY)) {
return 0;
}
if (type->tp_versions_used >= MAX_VERSIONS_PER_CLASS) {
return 0;
}
type->tp_versions_used++;
if (type->tp_flags & Py_TPFLAGS_IMMUTABLETYPE) {
/* static types */
if (NEXT_GLOBAL_VERSION_TAG > _Py_MAX_GLOBAL_TYPE_VERSION_TAG) {