Description

da-woods

opened on Nov 20, 2025

Issue body actions

Bug report

Bug description:

#include <Python.h>

static int
examplemodule_exec(PyObject *module) {
    // Yes I know there's no error checking...
    PyObject *gil_enabled = PySys_GetObject("_is_gil_enabled");
    PyObject *result = PyObject_CallNoArgs(gil_enabled);
    printf("gil enabled: ");
    PyObject_Print(result, stdout, 0);
    printf("\n");
    Py_DECREF(result);
    return 0;
}

static PyModuleDef_Slot examplemodule_slots[] = {
    {Py_mod_name, "examplemodule"},
    {Py_mod_gil, Py_MOD_GIL_USED},
    {Py_mod_exec, (void*)examplemodule_exec},
    {0}
};

PyMODEXPORT_FUNC
PyModExport_examplemodule(void)
{
    return examplemodule_slots;
}

I believe that the code above should print "gil enabled: True". However when I run it on Python 3.15.0a2 freethreading it prints "gil enabled: False".

I don't believe this is an issue in the old style PyInit_ initialization.

CPython versions tested on:

3.15

Operating systems tested on:

Linux

Linked PRs

• gh-141780: Make PyModule_FromSlotsAndSpec enable GIL if needed  #141785

Activity

1. da-woods

   added

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

   on Nov 20, 2025
2. da-woods

   changed the title [-]Disabling the GIL doesn't seem to work with PEP 793 initialization[/-] [+]Forcing enabling the GIL doesn't seem to work with PEP 793 initialization[/+] on Nov 20, 2025
3. da-woods commented on Nov 20, 2025

   

   da-woods

   on Nov 20, 2025

   ContributorAuthor

   More actions

   @encukou

   Reacted by Petr Viktorin
4. encukou

   self-assigned this

   on Nov 20, 2025
5. encukou

   added a commit that references this issue on Nov 20, 2025

   pythongh-141780: Make PyModule_FromSlotsAndSpec enable GIL if needed

   13faf0f
6. encukou commented on Nov 20, 2025

   

   encukou

   on Nov 20, 2025

   Member

   More actions

   Thanks for the catch!
7. StanFromIreland

   added

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

   on Nov 20, 2025
8. picnixz

   added

   3.15bugs and security fixesbugs and security fixes

   topic-free-threading

   on Nov 22, 2025
9. encukou

   added a commit that references this issue on Nov 24, 2025

   gh-141780: Make PyModule_FromSlotsAndSpec enable GIL if needed (GH-1…

   bf66bce
10. encukou

    closed this as completedon Nov 24, 2025
11. da-woods commented on Nov 24, 2025

    

    da-woods

    on Nov 24, 2025

    ContributorAuthor

    More actions

    Thanks
12. StanFromIreland

    added a commit that references this issue on Dec 6, 2025

    pythongh-141780: Make PyModule_FromSlotsAndSpec enable GIL if needed (…

    f614d18
13. ashm-dev

    added a commit that references this issue on Dec 8, 2025

    pythongh-141780: Make PyModule_FromSlotsAndSpec enable GIL if needed (…

    1fdf8af

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