This is a known issue, from the comment, but it is causing AVs for my embedded application when background threads are created, for example, by the _socket builtin module.
/* Undo the effect of Py_Initialize().
Beware: if multiple interpreter and/or thread states exist, these
are not wiped out; only the current thread and interpreter state
are deleted. But since everything else is deleted, those other
interpreter and thread states should no longer be used.
(XXX We should do better, e.g. wipe out all interpreters and
threads.)
Locking: as above.
*/
void
Py_Finalize(void)