Do sub interpreters actually work with c extensions? I get the extension API has long supported it. However, I wonder if in practice extensions rely on process

Do sub interpreters actually work with c extensions? I get the extension API has long supported it. However, I wonder if in practice extensions rely on process global state to stash information. If so, sub interpreters invite all kinds of nasty bugs. Keep in mind that porting the most popular extensions is an easy exercise so the more interesting question is how this hidden majority of extensions fares.