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Linecache updatecache can perform many useless os calls #140228
Description
Bug report
Bug description:
Consider the scenario where updatecache is called with a frozen module and module_globals is None.
In that case, _source_unavailable returns false because it is a frozen module, but because module_globals is None, the code carries on to look for the 'file' <frozen module> everywhere in sys.path. Compare that to the behavior prior to #132662 where that frozen module would simply return unavailable. I would recommend the following change:
if filename.startswith("<frozen ") and module_globals is not None:
# This is a frozen module, so we need to use the filename
# from the module globals.
fullname = module_globals.get("__file__")
if fullname is None:
print("fullname none")
return []Into
if filename.startswith("<frozen "):
if module_globals is None:
return []
# This is a frozen module, so we need to use the filename
# from the module globals.
fullname = module_globals.get("__file__")
if fullname is None:
print("fullname none")
return []For context, this is a problem for us because we run in a sandbox which restricts many OS operations, and this is performing useless os operations where it didn't prior to 3.14.
If there is agreement and it is helpful, happy to contribute a PR for this small change.
CPython versions tested on:
3.14
Operating systems tested on:
macOS, Windows, Linux
Activity
tconley1428 commentedon Oct 17, 2025
I would argue that
type-bugis appropriate. While in most cases the impact is limited to performance, for our use case the additional filesystem calls cause a failure.gaogaotiantian commentedon Oct 18, 2025
I did this PR and I agree this should be changed. Just move the comment to the start of the scope as module_globals check is related. If you want you can make a PR. Otherwise I’ll fix it myself soon.
gh-140228: Avoid making unnecessary syscalls in linecache for frozen …
pythongh-140228: Avoid making unnecessary syscalls in linecache for f…
[3.14] gh-140228: Avoid making unnecessary syscalls in linecache for …
StanFromIreland commentedon Nov 16, 2025
Triage: Can this be closed?
gaogaotiantian commentedon Nov 16, 2025
Thank you for checking it out, closed.
pythongh-140228: Avoid making unnecessary syscalls in linecache for f…