Description

assignee = None
closed_at = None
created_at = <Date 2008-10-25.02:52:43.004>
labels = ['expert-subinterpreters', 'type-bug']
title = '[subinterpreters] Multiple interpreters and readline module hook functions.'
updated_at = <Date 2020-05-15.01:28:36.744>
user = 'https://bugs.python.org/grahamd'

activity = <Date 2020-05-15.01:28:36.744>
actor = 'vstinner'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Subinterpreters']
creation = <Date 2008-10-25.02:52:43.004>
creator = 'grahamd'
dependencies = []
files = ['27727']
hgrepos = []
issue_num = 4202
keywords = ['patch']
message_count = 5.0
messages = ['75201', '107981', '173809', '173839', '368905']
nosy_count = 5.0
nosy_names = ['terry.reedy', 'vstinner', 'grahamd', 'Winston451', 'eric.snow']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue4202'
versions = ['Python 3.5', 'Python 3.6']

Activity

1. grahamd commented on Oct 25, 2008

   

   grahamdmannequin

   on Oct 25, 2008

   MannequinAuthor

   More actions

   Because the readline module uses PyGILState_Ensure() to facilitate triggering
   callbacks into Python code, this would make the ability to use the hook
   functions incompatible with use in sub interpreters.

   If this is the case, then that readline module cannot be used in sub
   interpreters should be documented if not already.

   Better still, attempts to register hooks from sub interpreters should result in
   an exception. Further, when in use, in sub interpreter, callback hooks should
   also not be called if defined, because if defined they would be the hooks from
   the main interpreter since variables holding the hooks are static C variables
   and shared across all interpreters.

   This issue derived from reading of code only and not tested in real program.
2. grahamd

   added

   interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)

   on Oct 25, 2008
3. terryjreedy commented on Jun 17, 2010

   

   terryjreedy

   on Jun 17, 2010

   Member

   More actions

   The be an issue, tests with currents interpreters are needed. You may be right, but it may be that no one ever uses readline with subinterpreters.
4. Winston451 commented on Oct 25, 2012

   

   Winston451mannequin

   on Oct 25, 2012

   Mannequin

   More actions

   Hi,

   I'm currently developping an application which runs sub interpreters in threads (one sub interpreter per thread). When I try to use readline completion in these sub interpreters it fails because it's not possible to import the "keyword" module (PyEval_GetRestricted() returns true). I think it is due to the fact that readline's on_completion() use PyGILState_Ensure(). It should be possible to use PyEval_RestoreThread with _PyOS_ReadlineTState instead.
5. Winston451 commented on Oct 26, 2012

   

   Winston451mannequin

   on Oct 26, 2012

   Mannequin

   More actions

   I attached a patch that solve the problem
6. Winston451

   added

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Oct 26, 2012
7. vstinner

   added

   topic-subinterpreters

   and removed

   interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)

   on May 15, 2020
8. vstinner

   changed the title [-]Multiple interpreters and readline module hook functions.[/-] [+][subinterpreters] Multiple interpreters and readline module hook functions.[/+] on May 15, 2020
9. vstinner commented on May 15, 2020

   

   vstinner

   on May 15, 2020

   Member

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   See also bpo-15751: [subinterpreters] Make the PyGILState API compatible with subinterpreters.
10. ezio-melotti

    transferred this issue fromon Apr 10, 2022
11. ezio-melotti

    added this to Subinterpreterson Apr 15, 2022
12. ezio-melotti

    moved this to Todo in Subinterpreterson Apr 15, 2022
13. ericsnowcurrently commented on Jul 8, 2024

    

    ericsnowcurrently

    on Jul 8, 2024

    Member

    More actions

    In the end, we kept the readline module single-phase init, which means it cannot be used in "isolated" subinterpreters (own GIL).
    Furthermore, @tonybaloney landed gh-112313 to resolve some of the complexity of the callbacks. I landed gh-121060 (3.13+) to force extensions to always be loaded in the main interpreter first, which resolves some of the other possible complexities. Overall, I believe this issue is sorted out.

    If we later want to work toward making the readline module work in multiple interpreters then I recommend we open a new issue.

    Reacted by Erlend E. Aasland
14. ericsnowcurrently

    closed this as completedon Jul 8, 2024
15. github-project-automation

    moved this from Todo to Done in Subinterpreterson Jul 8, 2024

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