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lib2to3 generation of pickle files is racy #85357
Description
| BPO | 41185 |
|---|---|
| Nosy | @barisione |
| Superseder | |
| Files |
Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.
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GitHub fields:
assignee = None
closed_at = <Date 2021-10-20.22:53:44.710>
created_at = <Date 2020-07-01.16:05:44.911>
labels = ['3.8', '3.7', 'expert-2to3', '3.9']
title = 'lib2to3 generation of pickle files is racy'
updated_at = <Date 2021-10-20.22:53:44.710>
user = 'https://github.com/barisione'bugs.python.org fields:
activity = <Date 2021-10-20.22:53:44.710>
actor = 'iritkatriel'
assignee = 'none'
closed = True
closed_date = <Date 2021-10-20.22:53:44.710>
closer = 'iritkatriel'
components = ['2to3 (2.x to 3.x conversion tool)']
creation = <Date 2020-07-01.16:05:44.911>
creator = 'barisione'
dependencies = []
files = ['49284']
hgrepos = []
issue_num = 41185
keywords = []
message_count = 1.0
messages = ['372760']
nosy_count = 1.0
nosy_names = ['barisione']
pr_nums = []
priority = 'normal'
resolution = 'wont fix'
stage = 'resolved'
status = 'closed'
superseder = '45544'
type = None
url = 'https://bugs.python.org/issue41185'
versions = ['Python 3.6', 'Python 3.7', 'Python 3.8', 'Python 3.9']
Activity
barisione commentedon Jul 1, 2020
The generation of pickle files in load_grammar in lib2to3/pgen2/driver.py is racy as other processes may end up reading a half-written pickle file.
This is reproducible with the command line tool, but it's easier to reproduce by importing lib2to3. You just need different processes importing lib2to3 at the same time to make this happen, see the attached reproducer.
I tried with Python 3.9 for completeness and, while it happens there as well, it seems to be less frequent ony my computer than when using Python 3.6 (2% failure rate instead of 50% failure rate).