Bug in InteractiveConsole /pickle

[fabioz]

BPO	8943
Nosy	@ncoghlan, @orsenthil, @fabioz, @avassalotti
Files	fast_test.py: Code showing the error. interative.py: Another code showing the error backtrace-py3k-8943.txt: preliminary gdb backtrace py3k pickle:save_global issue8943.diff: hg diff Doc/library/code.rst > issue8943.diff

^{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 = None
created_at = <Date 2010-06-08.16:24:21.604>
labels = ['3.8', 'type-bug', 'library', '3.9', '3.10']
title = 'Bug in InteractiveConsole /pickle'
updated_at = <Date 2020-10-28.14:13:37.445>
user = 'https://github.com/fabioz'

bugs.python.org fields:

activity = <Date 2020-10-28.14:13:37.445>
actor = 'holdenweb'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2010-06-08.16:24:21.604>
creator = 'fabioz'
dependencies = []
files = ['17589', '19734', '19735', '26917']
hgrepos = []
issue_num = 8943
keywords = ['patch']
message_count = 7.0
messages = ['107328', '107905', '108871', '121898', '121899', '121905', '168631']
nosy_count = 6.0
nosy_names = ['ncoghlan', 'orsenthil', 'fabioz', 'alexandre.vassalotti', 'iuridiniz', 'mjdorma']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'needs patch'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue8943'
versions = ['Python 3.8', 'Python 3.9', 'Python 3.10']

[fabioz]

Unable to pickle classes used in the InteractiveConsole. The code attached works in python 2.5 and fails on python 3.1.2.

[orsenthil]

Yes, the problem is observed in py3k. Pickle module when used via Interactive console is trying to import the class as __console__.ClassName and it is failing to see the __console__ module.

_pickle.PicklingError: Can't pickle <class '__console__.Example'>: import of module '__console__' failed

[avassalotti]

One easy fix for this would be to make InteractiveConsole use the string "__main__" instead of "__console__". But other than that, I don't think we can fix this within pickle.

[iuridiniz]

Bug stills on branch
http://svn.python.org/projects/python/branches/py3k
branch http://svn.python.org/projects/python/branches/release27-maint is OK

doing some gdb on 3.2, I have discovered that the problem occurs when trying to dump global Example from module __console__ on py3k/Modules/_pickle.c:save_global:2536

Python 2.7 never calls save_global (why?)

in annex: an update test

[iuridiniz]

preliminary gdb backtrace

[iuridiniz]

Well, this is a pickle problem or a Interactive console problem?

on python 2.7 does not save a type "type" (like Example class is)
2: type->tp_name = 0x58a87c "instance"
2: type->tp_name = 0x590391 "dict"
2: type->tp_name = 0x5943b6 "str"
2: type->tp_name = 0x5943b6 "str"

on python 3.2 does and when saving a type, it tries to save a global.

[mjdorma]

I'd suggest this is an issue in the doc for the InteractiveInterpreter class.

Try locals=global() and your problem goes away. (namespace == __main__)...