[Python-checkins] cpython (merge 3.2 -> default): Fix the fix for issue #12149: it was incorrect, although it had the side

[antoine.pitrou]

http://hg.python.org/cpython/rev/195bfd4c3ea1
changeset:   73979:195bfd4c3ea1
parent:      73977:54a77c556d9a
parent:      73978:b196bcd7c34f
user:        Antoine Pitrou <solipsis at pitrou.net>
date:        Thu Dec 15 14:17:36 2011 +0100
summary:
  Fix the fix for issue #12149: it was incorrect, although it had the side
effect of appearing to resolve the issue.  Thanks to Mark Shannon for
noticing.

files:
  Misc/NEWS            |   4 ++++
  Objects/typeobject.c |  18 ++++++++++--------
  2 files changed, 14 insertions(+), 8 deletions(-)


diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,10 @@
 Core and Builtins
 -----------------
 
+- Fix the fix for issue #12149: it was incorrect, although it had the side
+  effect of appearing to resolve the issue.  Thanks to Mark Shannon for
+  noticing.
+
 - Issue #13505: Pickle bytes objects in a way that is compatible with
   Python 2 when using protocols <= 2.
 
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -999,8 +999,6 @@
     assert(basedealloc);
     basedealloc(self);
 
-    PyType_Modified(type);
-
     /* Can't reference self beyond this point */
     Py_DECREF(type);
 
@@ -2776,15 +2774,16 @@
        for heaptypes. */
     assert(type->tp_flags & Py_TPFLAGS_HEAPTYPE);
 
-    /* The only field we need to clear is tp_mro, which is part of a
-       hard cycle (its first element is the class itself) that won't
-       be broken otherwise (it's a tuple and tuples don't have a
+    /* We need to invalidate the method cache carefully before clearing
+       the dict, so that other objects caught in a reference cycle
+       don't start calling destroyed methods.
+
+       Otherwise, the only field we need to clear is tp_mro, which is
+       part of a hard cycle (its first element is the class itself) that
+       won't be broken otherwise (it's a tuple and tuples don't have a
        tp_clear handler).  None of the other fields need to be
        cleared, and here's why:
 
-       tp_dict:
-           It is a dict, so the collector will call its tp_clear.
-
        tp_cache:
            Not used; if it were, it would be a dict.
 
@@ -2801,6 +2800,9 @@
            A tuple of strings can't be part of a cycle.
     */
 
+    PyType_Modified(type);
+    if (type->tp_dict)
+        PyDict_Clear(type->tp_dict);
     Py_CLEAR(type->tp_mro);
 
     return 0;

-- 
Repository URL: http://hg.python.org/cpython