Manipulate GIL to have Python thread work with pthread native ones

[dieter]

qshhnkf at alumni.sjtu.edu.cn writes:
... Python/C++ integration ...

When I learn about a task to integrate Python with C or C++,
I first think of "cython". "cython" facilitates those integrations.
Especially, it has annotations to control the GIL.

I have used "cython" for the implementation of a Python binding
to the XML security library. The result ist "dm.xmlsec.binding".
There, I use both ("cython") annotations to release the GIL when
passing over control from Python to C; as well as ("cython")
features to implement a callback from C to Python.