junyixie <[email protected]> added the comment:
> Which API should be used in C extensions to be "subinterpreter-safe"? ?>
> Currently, Py_None is a singleton shared by multiple interpreters. > > >
> Should suddenly all C extensions use a new Py_GetNone() function which >
> returns the per-interpreter singleton? If yes, that's basically what my > PR
> 18301 does:
> #define Py_None Py_GetNone()
after read you [WIP] bpo-39511: Add Py_GetNone() and Py_GetNoneRef() functions
#18301.
Actually, interp->none shared _Py_NoneStruct variable.
when two interperter modify interp->none refcount,will modify _Py_NoneStruct
variable.
> the CPU cacheline of common singletons like None, True and False can quickly
> become a performance bottleneck.
even if add Py_INCREF(none);.
In the scenario of parallel interpreter, will also have thread safety issues.
> PyStatus
> _Py_InitSingletons(PyThreadState *tstate)
> {
> PyObject *none = &_Py_NoneStruct;
> Py_INCREF(none);
> tstate->interp->none = none;
> return _PyStatus_OK();
> }
----------
nosy: +JunyiXie -Mark.Shannon, corona10, eric.snow, jeremy.kloth, jkloth,
larry, maciej.szulik, nanjekyejoannah, ncoghlan, phsilva, rhettinger,
shihai1991, steve.dower
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<https://bugs.python.org/issue39511>
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