Hello, While Lib/_threading_local.py is meant as a fallback Python implementation of thread-local objects, it looks like it will never be invoked in practice. The reason is that the thread-local code in Modules/_threadmodule.c in unconditionally compiled. Furthermore, _threading_local.py imports threading which itself imports _thread, so it's not possible for _threading_local to function if for some reason _thread fails to build or import. What should we do with _threading_local? Keep it as an example of a Python implementation (which is vastly slower than what a C implementation can do and also currently less robust), or plainly remove it? Regards Antoine.