diff -r 9e236a01e557 Lib/_threading_local.py
--- a/Lib/_threading_local.py	Wed Nov 04 08:38:12 2009 +0100
+++ b/Lib/_threading_local.py	Wed Nov 04 21:20:30 2009 +0100
@@ -218,10 +218,13 @@ class local(_localbase):
         key = object.__getattribute__(self, '_local__key')
 
         try:
-            threads = list(threading.enumerate())
+            # We can't call threading.enumerate() because it tries to take
+            # a lock which might already be taken (__del__ can be called at
+            # any point by the GC when collecting cycles).
+            threads = threading._active.values() + threading._limbo.values()
         except:
-            # If enumerate fails, as it seems to do during
-            # shutdown, we'll skip cleanup under the assumption
+            # If enumerating the current threads fails, as it seems to do
+            # during shutdown, we'll skip cleanup under the assumption
             # that there is nothing to clean up.
             return