[schmeii]

I don't think that is possible to activate the GIL only for one thread, it has to be activated process-wide.

But, if you want free-threading but you have to use an old extension that is not GIL-less, then you still can, by garding all access to this extension with a lock and setting the PYTHONGIL variable to 0.

But, you will need to compile the extension with --disable-gil or to obtain that from somewhere, if the extension author doesn't provide it, as the ABI of "standard" python and "--disable-gil" python is different.

How --disable-gil builds of python and of extensions will be distributed is not yet totally clear. I don't think pypi has already a clear idea of how to handle those extension, for instance.