Merged revisions 83918 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/branches/py3k

........
  r83918 | antoine.pitrou | 2010-08-10 00:38:19 +0200 (mar., 10 août 2010) | 5 lines

  Issue #3757: thread-local objects now support cyclic garbage collection.
  Thread-local objects involved in reference cycles will be deallocated
  timely by the cyclic GC, even if the underlying thread is still running.
........

Lib/test/test_threading_local.py

 import unittest
 from doctest import DocTestSuite
 from test import test_support
-threading = test_support.import_module('threading')
 import weakref
 import gc
 
+# Modules under test
+_thread = test_support.import_module('thread')
+threading = test_support.import_module('threading')
+import _threading_local
+
+
 class Weak(object):
     pass
 
@@ -13,7 +18,7 @@ def target(local, weaklist):
     local.weak = weak
     weaklist.append(weakref.ref(weak))
 
-class ThreadingLocalTest(unittest.TestCase):
+class BaseLocalTest:
 
     def test_local_refs(self):
         self._local_refs(20)
@@ -21,7 +26,7 @@ class ThreadingLocalTest(unittest.TestCase):
         self._local_refs(100)
 
     def _local_refs(self, n):
-        local = threading.local()
+        local = self._local()
         weaklist = []
         for i in range(n):
             t = threading.Thread(target=target, args=(local, weaklist))
@@ -32,9 +37,9 @@ class ThreadingLocalTest(unittest.TestCase):
         gc.collect()
         self.assertEqual(len(weaklist), n)
 
-        # XXX threading.local keeps the local of the last stopped thread alive.
+        # XXX _threading_local keeps the local of the last stopped thread alive.
         deadlist = [weak for weak in weaklist if weak() is None]
-        self.assertEqual(len(deadlist), n-1)
+        self.assertIn(len(deadlist), (n-1, n))
 
         # Assignment to the same thread local frees it sometimes (!)
         local.someothervar = None
@@ -48,7 +53,7 @@ class ThreadingLocalTest(unittest.TestCase):
         # is created but not correctly set on the object.
         # The first member set may be bogus.
         import time
-        class Local(threading.local):
+        class Local(self._local):
             def __init__(self):
                 time.sleep(0.01)
         local = Local()
@@ -69,7 +74,7 @@ class ThreadingLocalTest(unittest.TestCase):
 
     def test_derived_cycle_dealloc(self):
         # http://bugs.python.org/issue6990
-        class Local(threading.local):
+        class Local(self._local):
             pass
         locals = None
         passed = [False]
@@ -121,10 +126,32 @@ class ThreadingLocalTest(unittest.TestCase):
             self.assertRaises(TypeError, cls, 1)
 
 
+class ThreadLocalTest(unittest.TestCase, BaseLocalTest):
+    _local = _thread._local
+
+    # Fails for the pure Python implementation
+    def test_cycle_collection(self):
+        class X:
+            pass
+
+        x = X()
+        x.local = self._local()
+        x.local.x = x
+        wr = weakref.ref(x)
+        del x
+        gc.collect()
+        self.assertIs(wr(), None)
+
+
+class PyThreadingLocalTest(unittest.TestCase, BaseLocalTest):
+    _local = _threading_local.local
+
+
 def test_main():
     suite = unittest.TestSuite()
     suite.addTest(DocTestSuite('_threading_local'))
-    suite.addTest(unittest.makeSuite(ThreadingLocalTest))
+    suite.addTest(unittest.makeSuite(ThreadLocalTest))
+    suite.addTest(unittest.makeSuite(PyThreadingLocalTest))
 
     try:
         from thread import _local

Misc/NEWS

@@ -29,6 +29,10 @@ Core and Builtins
 Library
 -------
 
+- Issue #3757: thread-local objects now support cyclic garbage collection.
+  Thread-local objects involved in reference cycles will be deallocated
+  timely by the cyclic GC, even if the underlying thread is still running.
+
 - Issue #6231: Fix xml.etree.ElementInclude to include the tail of the
   current node.