Issue 31321: traceback.clear_frames() doesn't clear all frames (original) (raw)

Issue31321

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This issue has been migrated to GitHub: https://github.com/python/cpython/issues/75502

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process

Created on 2017-09-01 14:50 by vstinner, last changed 2022-04-11 14:58 by admin. This issue is now closed.

Messages (4)
msg301111 - (view)	Author: STINNER Victor (vstinner) *	Date: 2017-09-01 14:50
traceback.clear_frames(): "Clears the local variables of all the stack frames in a traceback tb by calling the clear() method of each frame object." https://docs.python.org/dev/library/traceback.html#traceback.clear_frames That's wrong: it only calls frame.clear() on the top frame of each traceback object. Output of attached clear_frames_bug.py script: --- locals: frame locals {'z': 3} frame locals {'y': 2} frame locals {'x': 1} clear_frames() locals: frame locals {} frame locals {'y': 2} frame locals {'x': 1} --- As you can see, only the locals of the func3() frame, where the exception was raised, is clear. Locals of other frames are not cleared. Attached PR fixes the issue. Output with the fix: --- locals: frame locals {'z': 3} frame locals {'y': 2} frame locals {'x': 1} clear_frames() locals: frame locals {} frame locals {} frame locals {} ---
msg301113 - (view)	Author: STINNER Victor (vstinner) *	Date: 2017-09-01 14:52
Would it be ok to backport such change to Python 3.6? It's a bugfix, no?
msg301114 - (view)	Author: STINNER Victor (vstinner) *	Date: 2017-09-01 14:53
traceback.clear_frames() was added by bpo-1565525: commit 173a157e725579eec1f28f8c9d53d6761ba6c79f.
msg301117 - (view)	Author: STINNER Victor (vstinner) *	Date: 2017-09-01 14:59
See bpo-31323 where I wanted to use traceback.clear_frames() to manually break a reference cycle.