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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Race condition when importing `collections.abc`","articleBody":"# Bug report\r\n\r\n### Bug description:\r\n\r\nDiscovered 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.\r\n\r\nTo trigger it, have a rust toolchain and Python installed, clone the PyO3 repo and execute the following command:\r\n\r\n```\r\nwhile RUST_BACKTRACE=1 UNSAFE_PYO3_BUILD_FREE_THREADED=1 cargo test --lib --features=full -- --test-threads=100; do :; done\r\n```\r\n\r\nYou may also hit some other test failures related to ZoneInfo, see the other issue I opened about that.\r\n\r\nYou will eventually see a test failure with the following text:\r\n\r\n```\r\n---- exceptions::socket::tests::gaierror stdout ----\r\nthread 'exceptions::socket::tests::gaierror' panicked at src/impl_/exceptions.rs:26:17:\r\nfailed 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)\r\n```\r\n\r\nI slightly modified PyO3 to get a traceback as well (hidden because it's a distractingly long diff):\r\n\r\n\r\n\u003cdetails\u003e\r\n\r\n```\r\ndiff --git a/src/impl_/exceptions.rs b/src/impl_/exceptions.rs\r\nindex 15b6f53b..de63ad59 100644\r\n--- a/src/impl_/exceptions.rs\r\n+++ b/src/impl_/exceptions.rs\r\n@@ -1,4 +1,8 @@\r\n-use crate::{sync::GILOnceCell, types::PyType, Bound, Py, Python};\r\n+use crate::{\r\n+    sync::GILOnceCell,\r\n+    types::{PyTracebackMethods, PyType},\r\n+    Bound, Py, Python,\r\n+};\r\n\r\n pub struct ImportedExceptionTypeObject {\r\n     imported_value: GILOnceCell\u003cPy\u003cPyType\u003e\u003e,\r\n@@ -20,8 +24,11 @@ impl ImportedExceptionTypeObject {\r\n             .import(py, self.module, self.name)\r\n             .unwrap_or_else(|e| {\r\n                 panic!(\r\n-                    \"failed to import exception {}.{}: {}\",\r\n-                    self.module, self.name, e\r\n+                    \"failed to import exception {}.{}: {}\\n{}\",\r\n+                    self.module,\r\n+                    self.name,\r\n+                    e,\r\n+                    e.traceback(py).unwrap().format().unwrap(),\r\n                 )\r\n             })\r\n     }\r\n```\r\n\r\n\u003c/details\u003e\r\n\r\nAnd the traceback is:\r\n\r\n```\r\nTraceback (most recent call last):\r\n  File \"/Users/goldbaum/.pyenv/versions/3.13.0t/lib/python3.13t/socket.py\", line 55, in \u003cmodule\u003e\r\n    import os, sys, io, selectors\r\n  File \"/Users/goldbaum/.pyenv/versions/3.13.0t/lib/python3.13t/selectors.py\", line 10, in \u003cmodule\u003e\r\n    from collections.abc import Mapping\r\n```\r\n\r\nSo somehow during setup of the `socket` module, `Mapping` isn't available yet, but only if many threads are simultaneously touching the Python runtime.\r\n\r\n(ping @davidhewitt, we probably want to disable the socket error tests on the free-threaded build as well)\r\n\r\n### CPython versions tested on:\r\n\r\n3.13\r\n\r\n### Operating systems tested on:\r\n\r\nmacOS\r\n\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-125415\n* gh-125944\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/ngoldbaum","@type":"Person","name":"ngoldbaum"},"datePublished":"2024-10-10T10:01:57.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":8},"url":"https://github.com/125245/cpython/issues/125245"}