logging.StreamHandler produces BrokenPipeError when cut short by head utility
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stdlib
type-bug
- Dominant language
- Python
- Stars
- 77.2k
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- 35.9k
- PR merge metrics
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Description
Bug report
Bug description:
The following code:
# test.py
import sys
import logging
logger = logging.getLogger(__name__)
logger.setLevel(logging.DEBUG)
logger.addHandler(logging.StreamHandler(sys.stdout))
logger.debug('foo')
logger.debug('bar')
when piped to head -n1, produces:
# python test.py | head -n1
foo
--- Logging error ---
Traceback (most recent call last):
File "/src/cpython/Lib/logging/__init__.py", line 1155, in emit
self.flush()
~~~~~~~~~~^^
File "/src/cpython/Lib/logging/__init__.py", line 1137, in flush
self.stream.flush()
~~~~~~~~~~~~~~~~~^^
BrokenPipeError: [Errno 32] Broken pipe
Call stack:
File "test.py", line 8, in <module>
logger.debug('bar')
Message: 'bar'
Arguments: ()
Exception ignored while flushing sys.stdout:
BrokenPipeError: [Errno 32] Broken pipe
This is because logging.StreamHandler.emit does not handle BrokenPipeError when flushing the stream.
I will fix this with the approach recommended by Note on SIGPIPE.
CPython versions tested on:
CPython main branch, 3.13
Operating systems tested on:
Linux
Linked PRs
- gh-134569
Contributor guide
First steps
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Research direction
The reported path is Lib/logging/init.py, especially StreamHandler.emit and flush; reproduce the issue with test.py piped to head -n1 on Linux. Compare the proposed fix in linked PR gh-134569 and its tests; done means the short pipeline no longer emits the logging traceback or final BrokenPipeError.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- tooling
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Clearly specified
- Newbie friendliness
- 25/100