From: Sam Gross <colesbury@gmail.com>
Date: Thu, 24 Oct 2024 22:12:51 +0000 (-0400)
Subject: gh-125245: Fix race condition when importing `collections.abc` (#125415)
X-Git-Tag: v3.14.0a2~307
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=fed501d7247053ce46a2ba512bf0e4bb4f483be6;p=thirdparty%2FPython%2Fcpython.git

gh-125245: Fix race condition when importing `collections.abc` (#125415)

If multiple threads concurrently imported `collections.abc`, some of the
threads might incorrectly see the "shim" `Lib/collections/abc.py` module
instead of the correct `Lib/_collections_abc.py` module.  This affected
both the free threading build and the default GIL-enabled build.
---

diff --git a/Lib/collections/__init__.py b/Lib/collections/__init__.py
index b47e728484c8..d688141f9b18 100644
--- a/Lib/collections/__init__.py
+++ b/Lib/collections/__init__.py
@@ -29,6 +29,9 @@ __all__ = [
 import _collections_abc
 import sys as _sys
 
+_sys.modules['collections.abc'] = _collections_abc
+abc = _collections_abc
+
 from itertools import chain as _chain
 from itertools import repeat as _repeat
 from itertools import starmap as _starmap
diff --git a/Lib/collections/abc.py b/Lib/collections/abc.py
deleted file mode 100644
index 034ba377a0db..000000000000
--- a/Lib/collections/abc.py
+++ /dev/null
@@ -1,3 +0,0 @@
-import _collections_abc
-import sys
-sys.modules[__name__] = _collections_abc
diff --git a/Misc/NEWS.d/next/Library/2024-10-11-00-40-13.gh-issue-125245.8vReM-.rst b/Misc/NEWS.d/next/Library/2024-10-11-00-40-13.gh-issue-125245.8vReM-.rst
new file mode 100644
index 000000000000..c880efe73d06
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-10-11-00-40-13.gh-issue-125245.8vReM-.rst
@@ -0,0 +1,2 @@
+Fix race condition when importing :mod:`collections.abc`, which could
+incorrectly return an empty module.