hang instead of pthread_exit during interpreter shutdown

[arielb1]

This mimics the Python 3.14 behavior and avoids crashes in Rust 1.84.

See python/cpython#87135 and rust-lang/rust#135929 and the related pyo3-log issue vorner/pyo3-log#30

By submitting these contributions you agree for them to be dual-licensed under PyO3's MIT OR Apache-2.0 license.

[codspeed-hq]

CodSpeed Performance Report

Merging #4874 will not alter performance

_{Comparing arielb1:safe-exit (c9dd539) with main (2c732a7)}

🎉 Hooray! codspeed-rust just leveled up to 2.7.2!

A heads-up, this is a breaking change and it might affect your current performance baseline a bit. But here's the exciting part - it's packed with new, cool features and promises improved result stability 🥳!
Curious about what's new? Visit our releases page to delve into all the awesome details about this new version.

Summary

✅ 85 untouched benchmarks

[arielb1]

Yay it passes tests.

[arielb1]

this change here is to avoid the test failing due to a high rate of assume failure (filter_too_much).

[arielb1]

split the test_double fix to #4879

[arielb1]

any update?

[Icxolu]

This looks fine to me, but I would like at least one other maintainers opinion (maybe @davidhewitt?) before proceeding here.

[davidhewitt]

Please forgive the delay, I will seek to review this on Friday, and ping me repeatedly from then if I do not achieve that!

[davidhewitt]

Thanks, I think let's move forward with this. The cfg guards hack around the various edge cases and, as I read it, the interaction with pthread_exit and rust destructors was (and still is) UB, so this just creates a practical solution for now. Ultimately 3.14 will make this problem go away.

[arielb1]

So the scary failure here is the CodSpeed regression?

[arielb1]

https://codspeed.io/PyO3/pyo3/benchmarks/pyo3-benches/benches/bench_extract.rs::benches::criterion_benchmark::extract_float_downcast_fail?branchId=67965f5d88fdfa8a702b59f1 looks kind of flaky to me.

[davidhewitt]

The failed stage is test-debug in https://github.com/PyO3/pyo3/actions/runs/13411900757/job/37463833819#step:9:8211, looks like the test might be triggering a debug build assertion?

I assume it's probably fine and we should just skip the new test on debug builds? After all, we're trying to test a bad edge case.

[davidhewitt]

Agreed RE flaky benchmark, I will set that one to be ignored.

[arielb1]

python: Python/pystate.c:345: void unbind_gilstate_tstate(PyThreadState *): Assertion `tstate == tstate_tss_get(&(tstate->interp->runtime)->autoTSSkey)' failed.

This looks bad. Not sure it's our fault tho. Trying to investigate - if it's PyO3's fault, we should fix it. I want to know whether it's a CPython or a PyO3 problem.

[arielb1]

I didn't manage to debug it easily, will try more after Rust Nation.