bpo-41984: GC track all user classes (GH-22701)

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Brandt Bucher 2020-10-14 18:44:07 -07:00 committed by GitHub
parent 302b6166fb
commit c13b847a6f
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5 changed files with 52 additions and 21 deletions

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@ -16,6 +16,15 @@ except ImportError:
raise TypeError('requires _testcapi.with_tp_del')
return C
try:
from _testcapi import without_gc
except ImportError:
def without_gc(cls):
class C:
def __new__(cls, *args, **kwargs):
raise TypeError('requires _testcapi.without_gc')
return C
from test import support
@ -94,9 +103,11 @@ class SimpleBase(NonGCSimpleBase):
assert self.id_ == id(self)
@without_gc
class NonGC(NonGCSimpleBase):
__slots__ = ()
@without_gc
class NonGCResurrector(NonGCSimpleBase):
__slots__ = ()
@ -109,8 +120,14 @@ class NonGCResurrector(NonGCSimpleBase):
class Simple(SimpleBase):
pass
class SimpleResurrector(NonGCResurrector, SimpleBase):
pass
# Can't inherit from NonGCResurrector, in case importing without_gc fails.
class SimpleResurrector(SimpleBase):
def side_effect(self):
"""
Resurrect self by storing self in a class-wide list.
"""
self.survivors.append(self)
class TestBase:
@ -178,6 +195,7 @@ class SimpleFinalizationTest(TestBase, unittest.TestCase):
self.assert_survivors([])
self.assertIs(wr(), None)
@support.cpython_only
def test_non_gc(self):
with SimpleBase.test():
s = NonGC()
@ -191,6 +209,7 @@ class SimpleFinalizationTest(TestBase, unittest.TestCase):
self.assert_del_calls(ids)
self.assert_survivors([])
@support.cpython_only
def test_non_gc_resurrect(self):
with SimpleBase.test():
s = NonGCResurrector()

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@ -582,9 +582,9 @@ class GCTests(unittest.TestCase):
self.assertTrue(gc.is_tracked(UserInt()))
self.assertTrue(gc.is_tracked([]))
self.assertTrue(gc.is_tracked(set()))
self.assertFalse(gc.is_tracked(UserClassSlots()))
self.assertFalse(gc.is_tracked(UserFloatSlots()))
self.assertFalse(gc.is_tracked(UserIntSlots()))
self.assertTrue(gc.is_tracked(UserClassSlots()))
self.assertTrue(gc.is_tracked(UserFloatSlots()))
self.assertTrue(gc.is_tracked(UserIntSlots()))
def test_is_finalized(self):
# Objects not tracked by the always gc return false

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@ -0,0 +1,2 @@
The garbage collector now tracks all user-defined classes. Patch by Brandt
Bucher.

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@ -3888,6 +3888,25 @@ with_tp_del(PyObject *self, PyObject *args)
return obj;
}
static PyObject *
without_gc(PyObject *Py_UNUSED(self), PyObject *obj)
{
PyTypeObject *tp = (PyTypeObject*)obj;
if (!PyType_Check(obj) || !PyType_HasFeature(tp, Py_TPFLAGS_HEAPTYPE)) {
return PyErr_Format(PyExc_TypeError, "heap type expected, got %R", obj);
}
if (PyType_IS_GC(tp)) {
// Don't try this at home, kids:
tp->tp_flags -= Py_TPFLAGS_HAVE_GC;
tp->tp_free = PyObject_Del;
tp->tp_traverse = NULL;
tp->tp_clear = NULL;
}
assert(!PyType_IS_GC(tp));
Py_INCREF(obj);
return obj;
}
static PyMethodDef ml;
static PyObject *
@ -5805,6 +5824,7 @@ static PyMethodDef TestMethods[] = {
{"meth_fastcall", (PyCFunction)(void(*)(void))meth_fastcall, METH_FASTCALL},
{"meth_fastcall_keywords", (PyCFunction)(void(*)(void))meth_fastcall_keywords, METH_FASTCALL|METH_KEYWORDS},
{"pynumber_tobase", pynumber_tobase, METH_VARARGS},
{"without_gc", without_gc, METH_O},
{NULL, NULL} /* sentinel */
};

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@ -2612,10 +2612,10 @@ type_new(PyTypeObject *metatype, PyObject *args, PyObject *kwds)
slots = NULL;
/* Initialize tp_flags */
// All heap types need GC, since we can create a reference cycle by storing
// an instance on one of its parents:
type->tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HEAPTYPE |
Py_TPFLAGS_BASETYPE;
if (base->tp_flags & Py_TPFLAGS_HAVE_GC)
type->tp_flags |= Py_TPFLAGS_HAVE_GC;
Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC;
/* Initialize essential fields */
type->tp_as_async = &et->as_async;
@ -2815,21 +2815,11 @@ type_new(PyTypeObject *metatype, PyObject *args, PyObject *kwds)
}
type->tp_dealloc = subtype_dealloc;
/* Enable GC unless this class is not adding new instance variables and
the base class did not use GC. */
if ((base->tp_flags & Py_TPFLAGS_HAVE_GC) ||
type->tp_basicsize > base->tp_basicsize)
type->tp_flags |= Py_TPFLAGS_HAVE_GC;
/* Always override allocation strategy to use regular heap */
type->tp_alloc = PyType_GenericAlloc;
if (type->tp_flags & Py_TPFLAGS_HAVE_GC) {
type->tp_free = PyObject_GC_Del;
type->tp_traverse = subtype_traverse;
type->tp_clear = subtype_clear;
}
else
type->tp_free = PyObject_Del;
type->tp_free = PyObject_GC_Del;
type->tp_traverse = subtype_traverse;
type->tp_clear = subtype_clear;
/* store type in class' cell if one is supplied */
cell = _PyDict_GetItemIdWithError(dict, &PyId___classcell__);