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Author pitrou
Recipients asvetlov, grahamd, mhammond, ncoghlan, pitrou
Date 2012-08-29.09:12:32
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In-reply-to <>
Le mercredi 29 août 2012 à 02:19 +0000, Nick Coghlan a écrit :
> However, it *doesn't* work (at least, not easily) if the extension
> itself wants to call back into an interpreter other than the one
> already associated with the current thread:
>    /* Embedding application (GIL always unlocked) */
>    gilstate = PyGILState_EnsureEx(interp_A);
>      /* Python code and extension code happens */
>        /* Callback needs to reach back into a specific interpreter */
>        cb_gilstate = PyGILState_EnsureEx(interp_B);
>          /* Callback runs */
>        PyGILState_Release(cb_gilstate);
>      /* Python code and extension code unwinds */
>    PyGILState_Release(gilstate);
> Does that second call to EnsureEx fail?

What would it fail? It should simply change the thread state to
interp_B's thread state for the current thread. Then the nested
PyGILState_Release changes the thread state back to its old value.

(of course, I don't understand how an extension running from a given
interpreter would have access to another interpreter's callback, but
regardless, it's technically not a problem)

> If it succeeds, how does the client know which interpreter to use for
> the PyGILState_Release call? It could be made to work if
> PyGILState_STATE was changed from an enum to a struct that included in
> interpreter state pointer, or if EnsureEx returned a different type
> and was paired up with a new ReleaseEx pointer.

Making PyGILState_STATE a struct sounds reasonable to me.

> However, that's starting to get very messy compared to a separate
> SwitchInterpreter call:

Why messy?
Date User Action Args
2012-08-29 09:12:37pitrousetrecipients: + pitrou, mhammond, ncoghlan, grahamd, asvetlov
2012-08-29 09:12:35pitroulinkissue15751 messages
2012-08-29 09:12:32pitroucreate