cpython: c9b7272e2553 (original) (raw)

Mercurial > cpython

changeset 104271:c9b7272e2553 3.5

ensure gc tracking is off when invoking weakref callbacks (closes #26617) [#26617]

Benjamin Peterson benjamin@python.org
date	Tue, 04 Oct 2016 00:00:02 -0700
parents	b24d0f274623
children	520cb70ecb90 b674fd340a23
files	Lib/test/test_weakref.py Misc/NEWS Objects/typeobject.c
diffstat	3 files changed, 24 insertions(+), 13 deletions(-)[+] [-] Lib/test/test_weakref.py 8 Misc/NEWS 2 Objects/typeobject.c 27

line wrap: on

line diff

--- a/Lib/test/test_weakref.py +++ b/Lib/test/test_weakref.py @@ -845,6 +845,14 @@ class ReferencesTestCase(TestBase): with self.assertRaises(AttributeError): ref1.callback = lambda ref: None

def test_callback_gcs(self):

   class ObjectWithDel(Object):[](#l1.8)

```
       def __del__(self): pass[](#l1.9)
```
```
   x = ObjectWithDel(1)[](#l1.10)
```

   ref1 = weakref.ref(x, lambda ref: support.gc_collect())[](#l1.11)

```
   del x[](#l1.12)
```
```
   support.gc_collect()[](#l1.13)
```

+ class SubclassableWeakrefTestCase(TestBase):

--- a/Misc/NEWS +++ b/Misc/NEWS @@ -10,6 +10,8 @@ Release date: TBA Core and Builtins ----------------- +- Issue #26617: Fix crash when GC runs during weakref callbacks. +

Issue #27942: String constants now interned recursively in tuples and frozensets.
Issue #21578: Fixed misleading error message when ImportError called with

--- a/Objects/typeobject.c +++ b/Objects/typeobject.c @@ -1123,11 +1123,6 @@ subtype_dealloc(PyObject *self) Py_TRASHCAN_SAFE_BEGIN(self); --_PyTrash_delete_nesting; -- tstate->trash_delete_nesting;

/* DO NOT restore GC tracking at this point. weakref callbacks

* (if any, and whether directly here or indirectly in something we[](#l3.8)

* call) may trigger GC, and if self is tracked at that point, it[](#l3.9)

* will look like trash to GC and GC will try to delete self again.[](#l3.10)

```
*/[](#l3.11)
```

/* Find the nearest base with a different tp_dealloc */ base = type; @@ -1138,30 +1133,36 @@ subtype_dealloc(PyObject *self) has_finalizer = type->tp_finalize || type->tp_del;

/* Maybe call finalizer; exit early if resurrected */
if (has_finalizer)

if (type->tp_finalize) { _PyObject_GC_TRACK(self);

if (type->tp_finalize) { if (PyObject_CallFinalizerFromDealloc(self) < 0) { /* Resurrected */ goto endlabel; }
}
/* If we added a weaklist, we clear it. Do this before calling

  tp_del, clearing slots, or clearing the instance dict. */[](#l3.31)

   _PyObject_GC_UNTRACK(self);[](#l3.32)

}
/*

 If we added a weaklist, we clear it. Do this *before* calling tp_del,[](#l3.35)

 clearing slots, or clearing the instance dict.[](#l3.36)

 GC tracking must be off at this point. weakref callbacks (if any, and[](#l3.38)

 whether directly here or indirectly in something we call) may trigger GC,[](#l3.39)

 and if self is tracked at that point, it will look like trash to GC and GC[](#l3.40)

 will try to delete self again.[](#l3.41)

*/ if (type->tp_weaklistoffset && !base->tp_weaklistoffset) PyObject_ClearWeakRefs(self);

if (type->tp_del) {

   _PyObject_GC_TRACK(self);[](#l3.47)
   type->tp_del(self);[](#l3.48)
   if (self->ob_refcnt > 0) {[](#l3.49)
       /* Resurrected */[](#l3.50)
       goto endlabel;[](#l3.51)
   }[](#l3.52)

   _PyObject_GC_UNTRACK(self);[](#l3.53)

} if (has_finalizer) {

   _PyObject_GC_UNTRACK(self);[](#l3.56)
   /* New weakrefs could be created during the finalizer call.[](#l3.57)
      If this occurs, clear them out without calling their[](#l3.58)
      finalizers since they might rely on part of the object[](#l3.59)