Issue #9945: logging: Fixed locking bugs in addHandler/removeHandler.
diff --git a/Lib/logging/__init__.py b/Lib/logging/__init__.py
index c8e5ac2..e1dbbc0 100644
--- a/Lib/logging/__init__.py
+++ b/Lib/logging/__init__.py
@@ -1263,20 +1263,23 @@
         """
         Add the specified handler to this logger.
         """
-        if not (hdlr in self.handlers):
-            self.handlers.append(hdlr)
+        _acquireLock()
+        try:
+            if not (hdlr in self.handlers):
+                self.handlers.append(hdlr)
+        finally:
+            _releaseLock()
 
     def removeHandler(self, hdlr):
         """
         Remove the specified handler from this logger.
         """
-        if hdlr in self.handlers:
-            #hdlr.close()
-            hdlr.acquire()
-            try:
+        _acquireLock()
+        try:
+            if hdlr in self.handlers:
                 self.handlers.remove(hdlr)
-            finally:
-                hdlr.release()
+        finally:
+            _releaseLock()
 
     def callHandlers(self, record):
         """
diff --git a/Misc/NEWS b/Misc/NEWS
index 77adf82..e6acb85 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -43,6 +43,8 @@
 Library
 -------
 
+- Issue #9945: logging: Fixed locking bugs in addHandler/removeHandler.
+
 - Issue #9936: Fixed executable lines' search in the trace module.
 
 - Issue #9928: Properly initialize the types exported by the bz2 module.