Reference leak in OSError when setting attributes before super().__init__ #150988
Description
Bug report
Bug description:
If an OSError subclass sets attributes on self prior to calling OSError.__init__ (or if __init__ is invoked multiple times) references are leaked. If OSError.__init__ is called before setting attributes no references are leaked.
import sys, gc
class LeakingOSError(OSError):
def __init__(self, code, message, filename, filename2):
self.strerror = message
self.filename = filename
self.filename2 = filename2
super().__init__(code, message, filename, None, filename2)
msg = "some error message"
filename = "some filename"
filename2 = "some filename 2"
refcount_msg = sys.getrefcount(msg)
refcount_filename = sys.getrefcount(filename)
refcount_filename2 = sys.getrefcount(filename2)
for _ in range(5):
try:
raise LeakingOSError(1, msg, filename, filename2)
except OSError:
pass
gc.collect()
print(f"msg refcount changed: expected {refcount_msg}, got {sys.getrefcount(msg)}")
print(f"filename refcount changed: expected {refcount_filename}, got {sys.getrefcount(filename)}")
print(f"filename2 refcount changed: expected {refcount_filename2}, got {sys.getrefcount(filename2)}")msg refcount changed: expected 4, got 9
filename refcount changed: expected 4, got 9
filename2 refcount changed: expected 4, got 9
This has been discovered in PyAV-Org/PyAV#2283
CPython versions tested on:
CPython main branch
Operating systems tested on:
macOS
Linked PRs
- gh-150988: Fix refleak in
OSErrorwhen attrs are set beforesuper().__init__#150990 - gh-150988: Fix OSError reference leak in oserror_init() #151219
- [3.15] gh-150988: Fix refleak in
OSErrorwhen attrs are set beforesuper().__init__()(GH-150990) #151240 - [3.14] gh-150988: Fix refleak in
OSErrorwhen attrs are set beforesuper().__init__()(GH-150990) #151241 - [3.13] gh-150988: Fix refleak in
OSErrorwhen attrs are set beforesuper().__init__()(GH-150990) #151242
Activity
[-]Reference leak in `OSError` when setting attributes before `super().__init_[/-][+]Reference leak in `OSError` when setting attributes before `super().__init__`[/+]pythongh-150988: Fix OSError reference leak in oserror_init()
gh-150988: Fix refleak in `OSError` when attrs are set before `super(…
vstinner commentedon Jun 10, 2026
Thanks for the bug report and the fix. It's now fixed.
[3.13] gh-150988: Fix refleak in `OSError` when attrs are set before …
[3.14] gh-150988: Fix refleak in `OSError` when attrs are set before …
[3.15] gh-150988: Fix refleak in `OSError` when attrs are set before …
pythongh-150988: Fix refleak in `OSError` when attrs are set before `…