Feature or enhancement

Proposal:

Currently it's impossible to call QueueListener.stop twice, you get a crash:

from queue import Queue
from logging import StreamHandler
from logging.handlers import (
    QueueHandler,
    QueueListener
)

sh = StreamHandler()
q = Queue(-1)
listener = QueueListener(
    q,
    sh,
    respect_handler_level=True
)
listener.start()
listener.stop()
listener.stop() # Crash here: 'NoneType' object has no attribute 'join'

But it may be desirable in some cases where you can't control at which point the termination will happen, you just want it to happen. For example, having it in multiple places: on app shutdown (normal behaviour) and atexit callbacks (backup in case shutdown wasn't planned and its callbacks didn't run).

This appears to be a simple "fix" (not that it's a bug) to

-        self.enqueue_sentinel()
-        self._thread.join()
-        self._thread = None
+        if self._thread:
+            self.enqueue_sentinel()
+            self._thread.join()
+            self._thread = None

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

No response

Linked PRs

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