python / python/cpython

logging.captureWarnings(True) doesn't show object allocation (-X tracemalloc)

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stdlib type-bug
Dominant language
Python
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Description

Bug report

When using logging.captureWarnings(True), the information about object allocation that you should get with -X tracemalloc gets lost.

It appears to be a discrepancy between Python and C implementation of the warnings module? source isn't passed to the created WarningMessage object in the Lib/warnings.py:
https://github.com/python/cpython/blob/a17cd47b614f8bc660788647a009a25e121221d7/Lib/warnings.py#L12
https://github.com/python/cpython/blob/a17cd47b614f8bc660788647a009a25e121221d7/Lib/warnings.py#L17
https://github.com/python/cpython/blob/a17cd47b614f8bc660788647a009a25e121221d7/Lib/warnings.py#L394
while it is in Python/_warnings.c:
https://github.com/python/cpython/blob/a17cd47b614f8bc660788647a009a25e121221d7/Python/_warnings.c#L593-L605

Reproduction steps:

  1. Create a file repro.py with contents:
import logging
import tempfile
import warnings

warnings.simplefilter("default", category=ResourceWarning)
logging.basicConfig()


print("--- UNCAPTURED WARNING ---")
file = tempfile.SpooledTemporaryFile(1)
file.write(b"foo")
file = None

print("\n--- CAPTURED WARNING ---")
logging.captureWarnings(True)
file = tempfile.SpooledTemporaryFile(1)
file.write(b"foo")
file = None
  1. Run python -X tracemalloc=5
  2. See that output only contains object allocation traceback for uncaptured warning:
--- UNCAPTURED WARNING ---
/tmp/test_tracemallo/repro.py:12: ResourceWarning: unclosed file <_io.BufferedRandom name=3>
  file = None
Object allocated at (most recent call last):
  File "/tmp/test_tracemallo/repro.py", lineno 11
    file.write(b"foo")
  File "/usr/lib/python3.10/tempfile.py", lineno 911
    self._check(file)
  File "/usr/lib/python3.10/tempfile.py", lineno 807
    self.rollover()
  File "/usr/lib/python3.10/tempfile.py", lineno 812
    newfile = self._file = TemporaryFile(**self._TemporaryFileArgs)
  File "/usr/lib/python3.10/tempfile.py", lineno 760
    return _io.open(fd, mode, buffering=buffering,

--- CAPTURED WARNING ---
WARNING:py.warnings:/tmp/test_tracemallo/repro.py:18: ResourceWarning: unclosed file <_io.BufferedRandom name=3>
  file = None

Your environment

  • CPython versions tested on: 3.7.13, 3.8.13, 3.9.13 (installed from deadsnakes ppa), 3.10.4 (system Python)
  • Operating system and architecture: Ubuntu 22.04
Linked PRs
  • gh-111451

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Compare WarningMessage construction in Lib/warnings.py with the corresponding handling in Python/_warnings.c, then run the provided repro.py command with -X tracemalloc=5. Done means warnings routed through logging.captureWarnings(True) retain the object-allocation traceback shown for uncaptured warnings.

Written by the indexing model from the issue text.

Assessment

Tech stack
c, python
Domain
backend
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Clearly specified
Newbie friendliness
25/100

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