Nothing between Release GIL and Reacquire GIL needs to change. Depending upon your extension, possibly nothing needs to change for the other steps either. Per S

Nothing between Release GIL and Reacquire GIL needs to change. Depending upon your extension, possibly nothing needs to change for the other steps either. Per Sam Gross: > Most C API extensions don’t require any changes, and for those that do require changes, the changes are small. For example, for “nogil” Python I’m providing binary wheels for ~35 extensions that are slow or difficult to build from source and only about seven projects required code changes (PyTorch, pybind11, Cython, numpy, scikit-learn, viztracer, pyo3). For four of those projects, the code changes have already been contributed and adopted upstream. For comparison, many of those same projects also frequently require changes to support minor releases of CPython. If you're using the GIL to protect access to non-Python objects, that will need to change. The PEP mentions a future HOWTO on how to updating existing extensions. I wish that were already written. There's disagreement among Python maintainers in the discussion thread on the PEP in how much work will be involved and I don't expect to resolve it here.