New submission from Terry J. Reedy <tjre...@udel.edu>:
Tool/scripts/find_recursionlimit.py includes test_cpickle() which, like the
other test_xxx functions, is supposed to raise a RuntimeError when the
recursion limit is reached. It appears to work correctly on 3.1 and I presume
previously. On 3.2, test_cpickle() hangs. Here is much reduced code that shows
the behavior:
import itertools
import io
import _pickle
# extracted from 'def test_cpickle' and condensed:
l = None
for n in itertools.count():
try:
raise KeyError
except KeyError:
for i in range(100):
l = [l]
print(n,i)
_pickle.Pickler(io.BytesIO(), protocol=-1).dump(l)
The added print line prints 0,99 1,99, ... indefinitely. If the recursive list
l is added to the print function, the attempt to create repr(l) raises a
runtime error at n = 9. If we remove the try-except part:
l = None
for n in itertools.count():
for i in range(100):
l = [l]
print(n,i)
_pickle.Pickler(io.BytesIO(), protocol=-1).dump(l)
*pickle* now raises a RuntimeError, as expected in the original context, at n=4!
1. I do not actually know which behavior is buggy. I suppose the next step
would be to capture and not toss the pickle output to see what is the
difference.
2. At least for the present, I think the call to test_cpickle should be
commented out in find_recursionlimit.py.
There seems to be other pickle and recursive structure issues, like #9269, but
I did not see any the same as this.
----------
files: frl_pickle1.py
messages: 126874
nosy: belopolsky, pitrou, terry.reedy
priority: normal
severity: normal
status: open
title: Bizarre pickle -- exception interaction bug
type: behavior
versions: Python 3.2
Added file: http://bugs.python.org/file20489/frl_pickle1.py
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<http://bugs.python.org/issue10987>
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