gh-114706: Allow QueueListener.stop() to be called more than once. (GH-114748)

Author: vsajip

Lib/logging/handlers.py

@@ -1586,6 +1586,7 @@ def stop(self):
         Note that if you don't call this before your application exits, there
         may be some records still left on the queue, which won't be processed.
         """
-        self.enqueue_sentinel()
-        self._thread.join()
-        self._thread = None
+        if self._thread:  # see gh-114706 - allow calling this more than once
+            self.enqueue_sentinel()
+            self._thread.join()
+            self._thread = None

Lib/test/test_logging.py

@@ -4089,6 +4089,7 @@ def test_queue_listener(self):
             self.que_logger.critical(self.next_message())
         finally:
             listener.stop()
+            listener.stop()  # gh-114706 - ensure no crash if called again
         self.assertTrue(handler.matches(levelno=logging.WARNING, message='1'))
         self.assertTrue(handler.matches(levelno=logging.ERROR, message='2'))
         self.assertTrue(handler.matches(levelno=logging.CRITICAL, message='3'))