Removal of private C-API breaks uwsgi compilation

[xrmx]

Bug report

Bug description:

Hello,

while trying to port uwsgi to 3.13 got this:

plugins/python/python_plugin.c: In function ‘uwsgi_python_pre_uwsgi_fork’:
plugins/python/python_plugin.c:1376:17: error: implicit declaration of function ‘_PyImport_AcquireLock’ [-Werror=implicit-function-declaration]
 1376 |                 _PyImport_AcquireLock(interp);
      |                 ^~~~~~~~~~~~~~~~~~~~~
plugins/python/python_plugin.c: In function ‘uwsgi_python_post_uwsgi_fork’:
plugins/python/python_plugin.c:1393:25: error: implicit declaration of function ‘_PyImport_ReleaseLock’ [-Werror=implicit-function-declaration]
 1393 |                         _PyImport_ReleaseLock(interp);
      |                         ^~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

Is there any other available API we can use?

I can make it compile by importing the internal header but does not look like a proper solution:

#if (PY_VERSION_HEX >= 0x030d0000)
#include "internal/pycore_import.h"
#endif

WIP branch is here https://github.com/unbit/uwsgi/tree/wip-py-313

cc @vstinner

CPython versions tested on:

3.13

Operating systems tested on:

Linux

[vstinner]

Why calling _PyImport_AcquireLock() in uwsgi_python_pre_uwsgi_fork(), instead of PyOS_BeforeFork()?

By the way, I'm not sure that it's safe to call PyOS_AfterFork_Child() in uwsgi_python_post_uwsgi_fork() without calling PyOS_BeforeFork().

[xrmx]

Why calling _PyImport_AcquireLock() in uwsgi_python_pre_uwsgi_fork(), instead of PyOS_BeforeFork()?

I think the code predates PyOS_BeforeFork by years 😅 and we didn't give it enough attention until it broke.

By the way, I'm not sure that it's safe to call PyOS_AfterFork_Child() in uwsgi_python_post_uwsgi_fork() without calling PyOS_BeforeFork().

Thanks

[vstinner]

Can you try PyOS_BeforeFork() and tell me how it goes?

[xrmx]

Opened a PR here, CI passes but haven't tested it unbit/uwsgi#2655