From: Donghee Na <donghee.na@python.org>
Date: Thu, 4 Sep 2025 17:19:30 +0000 (+0900)
Subject: gh-138192: Fix Context initialization so that all subinterpreters are assigned the... 
X-Git-Tag: v3.15.0a1~489
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=f070f54c5f4a42c7c61d1d5d3b8f3b7203b4a0fb;p=thirdparty%2FPython%2Fcpython.git

gh-138192: Fix Context initialization so that all subinterpreters are assigned the MISSING value. (gh-138503)

---------

Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
---

diff --git a/Lib/test/test_interpreters/test_api.py b/Lib/test/test_interpreters/test_api.py
index a34b20beaca7..289e607ad3fa 100644
--- a/Lib/test/test_interpreters/test_api.py
+++ b/Lib/test/test_interpreters/test_api.py
@@ -2204,6 +2204,16 @@ class LowLevelTests(TestBase):
             whence = eval(text)
             self.assertEqual(whence, _interpreters.WHENCE_LEGACY_CAPI)
 
+    def test_contextvars_missing(self):
+        script = f"""
+            import contextvars
+            print(getattr(contextvars.Token, "MISSING", "'doesn't exist'"))
+            """
+
+        orig = _interpreters.create()
+        text = self.run_and_capture(orig, script)
+        self.assertEqual(text.strip(), "<Token.MISSING>")
+
     def test_is_running(self):
         def check(interpid, expected):
             with self.assertRaisesRegex(InterpreterError, 'unrecognized'):
diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-09-05-01-19-04.gh-issue-138192.erluq5.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-09-05-01-19-04.gh-issue-138192.erluq5.rst
new file mode 100644
index 000000000000..05fa8edacd68
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2025-09-05-01-19-04.gh-issue-138192.erluq5.rst
@@ -0,0 +1,2 @@
+Fix :mod:`contextvars` initialization so that all subinterpreters are assigned the
+:attr:`~contextvars.Token.MISSING` value.
diff --git a/Python/context.c b/Python/context.c
index b764f5813fac..2f978b1c0abc 100644
--- a/Python/context.c
+++ b/Python/context.c
@@ -1360,11 +1360,8 @@ get_token_missing(void)
 PyStatus
 _PyContext_Init(PyInterpreterState *interp)
 {
-    if (!_Py_IsMainInterpreter(interp)) {
-        return _PyStatus_OK();
-    }
-
     PyObject *missing = get_token_missing();
+    assert(PyUnstable_IsImmortal(missing));
     if (PyDict_SetItemString(
         _PyType_GetDict(&PyContextToken_Type), "MISSING", missing))
     {