@remilapeyre
sorry about the fail.

I have already fixed the test error! This PR could be reviewed and merged right now.

this PR needs backport to 3.0-3.7 and 2.7

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

And if you don't make the requested changes, you will be poked with soft cushions!

I have made the requested changes; please review again

Thanks for making the requested changes!

@vsajip: please review the changes made to this pull request.

I have made the requested changes; please review again

Thanks for making the requested changes!

@vsajip: please review the changes made to this pull request.

@vsajip this PR need be back to Python 3.5/3.6/3.7

3.5 and 3.6 are in security fixes only mode so this can be backported only to 3.7.

@tirkarthi Got it, thx

@Zheaoli @vsajip I am just curious if there is a test for this in test_logging or as a separate PR? I hope below script illustrates the issue.

import queue
import logging
from logging import handlers

queue = queue.Queue(-1)

que_hdlr = handlers.QueueHandler(queue)
stream_hdlr = logging.StreamHandler()

logger = logging.getLogger(__name__)
queue_log_format = "Queue %(name)s -> %(levelname)s: %(message)s"
queue_formatter = logging.Formatter(queue_log_format)
stream_log_format = "Stream %(name)s -> %(levelname)s: %(message)s"
stream_formatter = logging.Formatter(stream_log_format)

stream_hdlr.setFormatter(stream_formatter)
que_hdlr.setFormatter(queue_formatter)

listener = handlers.QueueListener(queue, que_hdlr)
listener.start()

logger.setLevel(logging.WARNING)
logger.addHandler(que_hdlr)
logger.addHandler(stream_hdlr)

logger.exception("hello")

➜  cpython git:(master) ✗ python3.7 /tmp/foo.py
Stream __main__ -> ERROR: Queue __main__ -> ERROR: hello
NoneType: None
➜  cpython git:(master) ✗ ./python.exe /tmp/foo.py # patched master
Stream __main__ -> ERROR: hello
NoneType: None

I can raise a PR something along the lines of below if there is a confirmation that there are no tests for the current PR.

@unittest.skipUnless(hasattr(logging.handlers, 'QueueListener'),
                     'logging.handlers.QueueListener required for this test')
def test_queue_listener_with_multiple_handlers(self):
    # Test that queue handler format doesn't affect other handler formats ([bpo-35726](https://bugs.python.org/issue35726)).
    self.que_hdlr.setFormatter(self.root_formatter)
    self.que_logger.addHandler(self.root_hdlr)

    listener = logging.handlers.QueueListener(self.queue, self.que_hdlr)
    listener.start()
    self.que_logger.error("error")
    listener.stop()
    self.assertEqual(self.stream.getvalue().strip(), "que -> ERROR: error")

• Without patch

./python.exe -m unittest -v test.test_logging.QueueHandlerTest.test_queue_listener_with_multiple_handlers
test_queue_listener_with_multiple_handlers (test.test_logging.QueueHandlerTest) ... FAIL

======================================================================
FAIL: test_queue_listener_with_multiple_handlers (test.test_logging.QueueHandlerTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/karthikeyansingaravelan/stuff/python/cpython/Lib/test/test_logging.py", line 3519, in test_queue_listener_with_multiple_handlers
    self.assertEqual(self.stream.getvalue().strip(), "que -> ERROR: error")
AssertionError: 'que -> ERROR: que -> ERROR: error' != 'que -> ERROR: error'
- que -> ERROR: que -> ERROR: error
+ que -> ERROR: error


----------------------------------------------------------------------
Ran 1 test in 0.009s

FAILED (failures=1)

• With patch

./python.exe -m unittest -v test.test_logging.QueueHandlerTest.test_queue_listener_with_multiple_handlers
test_queue_listener_with_multiple_handlers (test.test_logging.QueueHandlerTest) ... ok

----------------------------------------------------------------------
Ran 1 test in 0.005s

OK

A PR with a test would be good, thanks. I don't believe there was a test for this specific case.

Thanks @Zheaoli for the PR, and @vsajip for merging it 🌮🎉.. I'm working now to backport this PR to: 3.7.
🐍🍒⛏🤖

GH-12716 is a backport of this pull request to the 3.7 branch.