[Python-checkins] r85393 - in python/branches/release27-maint: Doc/reference/datamodel.rst Lib/test/test_module.py Misc/NEWS Objects/moduleobject.c

Wed Oct 13 01:02:35 CEST 2010

Author: benjamin.peterson
Date: Wed Oct 13 01:02:35 2010
New Revision: 85393
Log:
Merged revisions 85392 via svnmerge from 
svn+ssh://pythondev@svn.python.org/python/branches/py3k
........
 r85392 | benjamin.peterson | 2010年10月12日 17:57:59 -0500 (2010年10月12日) | 1 line
 
 prefer clearing global objects to obscure module.__dict__ bugs #10068
........
Modified:
 python/branches/release27-maint/ (props changed)
 python/branches/release27-maint/Doc/reference/datamodel.rst
 python/branches/release27-maint/Lib/test/test_module.py
 python/branches/release27-maint/Misc/NEWS
 python/branches/release27-maint/Objects/moduleobject.c
Modified: python/branches/release27-maint/Doc/reference/datamodel.rst
==============================================================================

--- python/branches/release27-maint/Doc/reference/datamodel.rst	(original)
+++ python/branches/release27-maint/Doc/reference/datamodel.rst	Wed Oct 13 01:02:35 2010
@@ -739,6 +739,13 @@
 Special read-only attribute: :attr:`__dict__` is the module's namespace as a
 dictionary object.
 
+ .. impl-detail::
+
+ Because of the way CPython clears module dictionaries, the module
+ dictionary will be cleared when the module falls out of scope even if the
+ dictionary still has live references. To avoid this, copy the dictionary
+ or keep the module around while using its dictionary directly.
+
 .. index::
 single: __name__ (module attribute)
 single: __doc__ (module attribute)
Modified: python/branches/release27-maint/Lib/test/test_module.py
==============================================================================
--- python/branches/release27-maint/Lib/test/test_module.py	(original)
+++ python/branches/release27-maint/Lib/test/test_module.py	Wed Oct 13 01:02:35 2010
@@ -1,6 +1,6 @@
 # Test the module type
 import unittest
-from test.test_support import run_unittest
+from test.test_support import run_unittest, gc_collect
 
 import sys
 ModuleType = type(sys)
@@ -55,14 +55,29 @@
 {"__name__": "foo", "__doc__": "foodoc", "bar": 42})
 self.assertTrue(foo.__dict__ is d)
 
+ @unittest.expectedFailure
 def test_dont_clear_dict(self):
 # See issue 7140.
 def f():
 foo = ModuleType("foo")
 foo.bar = 4
 return foo
+ gc_collect()
 self.assertEqual(f().__dict__["bar"], 4)
 
+ def test_clear_dict_in_ref_cycle(self):
+ destroyed = []
+ m = ModuleType("foo")
+ m.destroyed = destroyed
+ s = """class A:
+ def __del__(self):
+ destroyed.append(1)
+a = A()"""
+ exec(s, m.__dict__)
+ del m
+ gc_collect()
+ self.assertEqual(destroyed, [1])
+
 def test_main():
 run_unittest(ModuleTests)
 
Modified: python/branches/release27-maint/Misc/NEWS
==============================================================================
--- python/branches/release27-maint/Misc/NEWS	(original)
+++ python/branches/release27-maint/Misc/NEWS	Wed Oct 13 01:02:35 2010
@@ -10,6 +10,9 @@
 Core and Builtins
 -----------------
 
+- Issue #10068: Global objects which have reference cycles with their module's
+ dict are now cleared again. This causes issue #7140 to appear again.
+
 - Issue #9869: Make long() and PyNumber_Long return something of type
 long for a class whose __long__ method returns a plain int. This
 fixes an interpreter crash when initializing an instance of a long
Modified: python/branches/release27-maint/Objects/moduleobject.c
==============================================================================
--- python/branches/release27-maint/Objects/moduleobject.c	(original)
+++ python/branches/release27-maint/Objects/moduleobject.c	Wed Oct 13 01:02:35 2010
@@ -175,10 +175,7 @@
 {
 PyObject_GC_UnTrack(m);
 if (m->md_dict != NULL) {
- /* If we are the only ones holding a reference, we can clear
- the dictionary. */
- if (Py_REFCNT(m->md_dict) == 1)
- _PyModule_Clear((PyObject *)m);
+ _PyModule_Clear((PyObject *)m);
 Py_DECREF(m->md_dict);
 }
 Py_TYPE(m)->tp_free((PyObject *)m);
