From Gitter:

Newby question... is PyAV compatible with python sub-interpreters? According to the python docs https://docs.python.org/3/c-api/init.html using PyGILState_Ensure(), for example, is not compatible and I see this in the generated .c files inside #ifdef WITH_THREAD. I am trying to use PyAV inside a Django wsgi app and running into intermittent hang problems. Thanks in advance for your help.

I see that PyGILState_Ensure is called by __Pyx_RefNannySetupContext in every file. There are only 4 places that is called with acquire_gil being non-zero:

src/av/container/pyio.c: __Pyx_RefNannySetupContext("pyio_read", 1);
src/av/container/pyio.c: __Pyx_RefNannySetupContext("pyio_write", 1);
src/av/container/pyio.c: __Pyx_RefNannySetupContext("pyio_seek", 1);
src/av/logging.c: __Pyx_RefNannySetupContext("log_callback", 1);

So... if you don't use Python based IO, and disable the logging system, that should be clear.

This triggers it in each of the input/output containers, but I don't think control reaches it. Same with utils. This is another with gil in logging.

Okay... so there isn't a user-exposed way to disable the logging system adequately enough. We would have to restructure the Frame._init method just a bit to avoid the with gil, and add another method to logging to disable it entirely (or maybe check an envvar or something).

At that point, I don't think it will get called (if you avoid Python IO)