Thanks to recent enhancements, epecially in bpo-46417, the last memory blocks are now released at Python exit! The initial issue has been fixed!!! This bug was 15 years old! Current main branch:

$ ./python -I -X showrefcount -c pass
[-5 refs, 0 blocks]

"0 blocks" means that Python no longer leaks memory at exit. You can use Valgrind to check it ;-)

The negative reference count is being discussed in bpo-46449.

I close this issue since it has an insane history: too many pull requests, changes, etc.

While the work is not 100% done (we need to convert remaining static types to heap types, and convert extensions to multi-phase init), I prefer to address remaining issues in (existing or new) separated issues. See for example the bpo-40077: "Convert static types to heap types: use PyType_FromSpec()".

I would like to thank everybody who helped to fix this issue! It's hard to list all names since this issue is a meta issues made of many sub-issues which also have sub-issues. Authors of PEP 573 and PEP 630 also helped fixing this issue!