Bug report

Bug description:

Discovered alongside#125243 with similar steps to reproduce. I don't have a simpler way to trigger this than "run the PyO3 tests in a loop" because I think it requires many threads accessing the python runtime simulatenously.

To trigger it, have a rust toolchain and Python installed, clone the PyO3 repo and execute the following command:

while RUST_BACKTRACE=1 UNSAFE_PYO3_BUILD_FREE_THREADED=1 cargo test --lib --features=full -- --test-threads=100; do :; done

You may also hit some other test failures related to ZoneInfo, see the other issue I opened about that.

You will eventually see a test failure with the following text:

---- exceptions::socket::tests::gaierror stdout ----thread 'exceptions::socket::tests::gaierror' panicked at src/impl_/exceptions.rs:26:17:failed to import exception socket.gaierror: ImportError: cannot import name 'Mapping' from 'collections.abc' (/Users/goldbaum/.pyenv/versions/3.13.0t/lib/python3.13t/collections/abc.py)

I slightly modified PyO3 to get a traceback as well (hidden because it's a distractingly long diff):

diff --git a/src/impl_/exceptions.rs b/src/impl_/exceptions.rsindex 15b6f53b..de63ad59 100644--- a/src/impl_/exceptions.rs+++ b/src/impl_/exceptions.rs@@ -1,4 +1,8 @@-use crate::{sync::GILOnceCell, types::PyType, Bound, Py, Python};+use crate::{+    sync::GILOnceCell,+    types::{PyTracebackMethods, PyType},+    Bound, Py, Python,+}; pub struct ImportedExceptionTypeObject {     imported_value: GILOnceCell<Py<PyType>>,@@ -20,8 +24,11 @@ impl ImportedExceptionTypeObject {             .import(py, self.module, self.name)             .unwrap_or_else(|e| {                 panic!(-                    "failed to import exception {}.{}: {}",-                    self.module, self.name, e+                    "failed to import exception {}.{}: {}\n{}",+                    self.module,+                    self.name,+                    e,+                    e.traceback(py).unwrap().format().unwrap(),                 )             })     }

And the traceback is:

Traceback (most recent call last):  File "/Users/goldbaum/.pyenv/versions/3.13.0t/lib/python3.13t/socket.py", line 55, in <module>    import os, sys, io, selectors  File "/Users/goldbaum/.pyenv/versions/3.13.0t/lib/python3.13t/selectors.py", line 10, in <module>    from collections.abc import Mapping

So somehow during setup of thesocket module,Mapping isn't available yet, but only if many threads are simultaneously touching the Python runtime.

(ping@davidhewitt, we probably want to disable the socket error tests on the free-threaded build as well)

CPython versions tested on:

3.13

Operating systems tested on:

macOS

Linked PRs

• gh-125245: Fix race condition when importingcollections.abc #125415
• [3.13] gh-125245: Fix race condition when importingcollections.abc (GH-125415) #125944