Issue #9501: Fixed logging regressions in cleanup code.

Lib/logging/__init__.py

@@ -609,6 +609,10 @@ def _removeHandlerRef(wr):
     """
     Remove a handler reference from the internal cleanup list.
     """
+    # This function can be called during module teardown, when globals are
+    # set to None. If _acquireLock is None, assume this is the case and do
+    # nothing.
+    if _acquireLock is not None:
         _acquireLock()
         try:
             if wr in _handlerList:
@@ -1604,8 +1608,16 @@ def shutdown(handlerList=_handlerList):
         #we just ignore them if raiseExceptions is not set
         try:
             h = wr()
+            if h:
+                try:
                     h.flush()
                     h.close()
+                except (IOError, ValueError):
+                    # Ignore errors which might be caused
+                    # because handlers have been closed but
+                    # references to them are still around at
+                    # application exit.
+                    pass
         except:
             if raiseExceptions:
                 raise

Misc/NEWS

@@ -123,6 +123,8 @@ Extensions
 Library
 -------
 
+- Issue #9501: Fixed logging regressions in cleanup code.
+
 - Fix functools.total_ordering() to actually work.
 
 - Issue #9572: Importlib should not raise an exception if a directory it