The CPython API is such a dumpster fire, even writing very simple modules the reference counting is very difficult to do correctly. The majority of python modules written in C are probably leaking memory somewhere but nobody knows.

My problem is that debugging a segfault in a Python system is impossible because of all the noise generated by Python modules that never bothered to clean up their Valgrind output.

Some tricks that worked for me in the past:

1. use rr for debugging your binary wheel, you can set up watchpoints, and reverse step/continue from the segfault.

2. compile and run your wheel with sanitizers (ASAN, UBSAN).

I rarely use valgrind so I can't comment on that.