New submission from Ben <benjsim...@gmail.com>:
When running the attached on 3.8 and 3.9 (master) I get the following:
Process Process-3:
Traceback (most recent call last):
File
"/home/bjs/.pyenv/versions/3.9-dev/lib/python3.9/multiprocessing/process.py",
line 313, in _bootstrap
self.run()
File
"/home/bjs/.pyenv/versions/3.9-dev/lib/python3.9/multiprocessing/process.py",
line 108, in run
self._target(*self._args, **self._kwargs)
File
"/home/bjs/Downloads/e4671450a50df5a0648c6dda0c7b642a-3db67c29d8d9e6a6d629c2c016f5853ec22000ed/test.py",
line 14, in g
X[0]
File
"/home/bjs/.pyenv/versions/3.9-dev/lib/python3.9/multiprocessing/shared_memory.py",
line 413, in __getitem__
(v,) = struct.unpack_from(
ValueError: not enough values to unpack (expected 1, got 0)
(Tested on Windows and Linux)
Either this is a documentation error, and the docs for shared_memory should
state that the ShareableList does not have atomic operations and so this is
unsafe, or this is a suspicious behaviour. I'm not sure which.
I could also just be using the library totally incorrectly.
----------
files: test.py
messages: 348299
nosy: bjs
priority: normal
severity: normal
status: open
title: Multiprocessing shared_memory ValueError on race with ShareableList
type: behavior
versions: Python 3.8, Python 3.9
Added file: https://bugs.python.org/file48496/test.py
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue37652>
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