Fewer than people expect. For example, the += operator looks atomic, but under the hood, it's made up of multiple python bytecode instructions, so the GIL won't apply here.
> For example, the += operator looks atomic, but under the hood, it's made up of multiple python bytecode instructions, so the GIL won't apply here.
Sure, but any call to a native function which doesn’t release the gil (which is most of them at least for the builtins) is currently atomic so something like dict.setdefault.
