Let's check the buildbot failure before merging this:#128640 (comment)

That failure looks related, but I have absolutely no idea how.

I suppose that this change should not be merged, since you proposed a revert for the same change in the main branch:#134256

!buildbot iOS

🤖 New build scheduled with the buildbot fleet by@ZeroIntensity for commit76bcc46 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F134254%2Fmerge

The command will test the builders whose names match following regular expression:iOS

The builders matched are:

• iOS ARM64 Simulator PR

I'm going to run the buildbots to see if the crash is somehow related to something else on 3.15. I'm still pretty lost on what could be the cause. I can only see two possibilities:

• We revealed an existing bug with_PyThreadState_DeleteList and/or_PyThreadState_RemoveExcept.
• The embedding test revealed a bug with the implementation, but I'm not sure what. Maybe I broke destroying interpreters with only one thread state?

I'm not sure if it's related, but the iOS buildbot has also been experiencing another intermittent subinterpreters failure:#127108. The most recent instance was in#125962 (comment).

In this specific case, the change was related. It's reverted on main. I haven't had time to look into those other failures yet.