gh-136421: Load _datetime static types during interpreter initialization

Include/internal/pycore_pylifecycle.h

@@ -41,6 +41,7 @@ extern PyStatus _Py_HashRandomization_Init(const PyConfig *);
 
 extern PyStatus _PyGC_Init(PyInterpreterState *interp);
 extern PyStatus _PyAtExit_Init(PyInterpreterState *interp);
+extern PyStatus _PyDateTime_InitTypes(PyInterpreterState *interp);
 
 /* Various internal finalizers */
 

Lib/test/datetimetester.py

@@ -3651,6 +3651,25 @@ def test_repr_subclass(self):
         td = SubclassDatetime(2010, 10, 2, second=3)
         self.assertEqual(repr(td), "SubclassDatetime(2010, 10, 2, 0, 0, 3)")
 
+    @support.cpython_only
+    def test_concurrent_initialization(self):
+        # Run in a subprocess to ensure we get a clean version of _datetime
+        script = """if True:
+        from concurrent.futures import InterpreterPoolExecutor
+
+        def func():
+            import _datetime
+            print('a', end='')
+
+        with InterpreterPoolExecutor() as executor:
+            for _ in range(8):
+                executor.submit(func)
+        """
+        rc, out, err = script_helper.assert_python_ok("-c", script)
+        self.assertEqual(rc, 0)
+        self.assertEqual(out, b"a" * 8)
+        self.assertEqual(err, b"")
+
 
 class TestSubclassDateTime(TestDateTime):
     theclass = SubclassDatetime

Misc/NEWS.d/next/Core_and_Builtins/2025-07-12-09-59-14.gh-issue-136421.ZD1rNj.rst

@@ -0,0 +1 @@
+Fix crash when initializing :mod:`datetime` concurrently.

Modules/Setup.bootstrap.in

@@ -12,6 +12,8 @@ posix posixmodule.c
 _signal signalmodule.c
 _tracemalloc _tracemalloc.c
 _suggestions _suggestions.c
+# needs libm and on some platforms librt
+_datetime _datetimemodule.c
 
 # modules used by importlib, deepfreeze, freeze, runpy, and sysconfig
 _codecs _codecsmodule.c

Modules/Setup.stdlib.in

@@ -56,9 +56,6 @@
 @MODULE_CMATH_TRUE@cmath cmathmodule.c
 @MODULE__STATISTICS_TRUE@_statistics _statisticsmodule.c
 
-# needs libm and on some platforms librt
-@MODULE__DATETIME_TRUE@_datetime _datetimemodule.c
-
 # _decimal uses libmpdec
 # either static libmpdec.a from Modules/_decimal/libmpdec or libmpdec.so
 # with ./configure --with-system-libmpdec

Modules/_datetimemodule.c

@@ -14,6 +14,7 @@
 #include "pycore_object.h"        // _PyObject_Init()
 #include "pycore_time.h"          // _PyTime_ObjectToTime_t()
 #include "pycore_unicodeobject.h" // _PyUnicode_Copy()
+#include "pycore_initconfig.h"    // _PyStatus_OK()
 
 #include "datetime.h"
 
@@ -7329,13 +7330,9 @@ clear_state(datetime_state *st)
 }
 
 
-static int
-init_static_types(PyInterpreterState *interp, int reloading)
+PyStatus
+_PyDateTime_InitTypes(PyInterpreterState *interp)
 {
-    if (reloading) {
-        return 0;
-    }
-
     // `&...` is not a constant expression according to a strict reading
     // of C standards. Fill tp_base at run-time rather than statically.
     // See https://bugs.python.org/issue40777
@@ -7347,11 +7344,11 @@ init_static_types(PyInterpreterState *interp, int reloading)
     for (size_t i = 0; i < Py_ARRAY_LENGTH(capi_types); i++) {
         PyTypeObject *type = capi_types[i];
         if (_PyStaticType_InitForExtension(interp, type) < 0) {
-            return -1;
+            return _PyStatus_ERR("could not initialize static types");
         }
     }
 
-    return 0;
+    return _PyStatus_OK();
 }
 
 
@@ -7379,10 +7376,6 @@ _datetime_exec(PyObject *module)
     }
     /* We actually set the "current" module right before a successful return. */
 
-    if (init_static_types(interp, reloading) < 0) {
-        goto error;
-    }
-
     for (size_t i = 0; i < Py_ARRAY_LENGTH(capi_types); i++) {
         PyTypeObject *type = capi_types[i];
         const char *name = _PyType_Name(type);

PCbuild/_freeze_module.vcxproj

@@ -106,6 +106,7 @@
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="..\Modules\atexitmodule.c" />
+    <ClCompile Include="..\Modules\_datetimemodule.c" />
     <ClCompile Include="..\Modules\faulthandler.c" />
     <ClCompile Include="..\Modules\gcmodule.c" />
     <ClCompile Include="..\Modules\getbuildinfo.c" />

Python/pylifecycle.c

@@ -760,6 +760,11 @@ pycore_init_types(PyInterpreterState *interp)
         return status;
     }
 
+    status = _PyDateTime_InitTypes(interp);
+    if (_PyStatus_EXCEPTION(status)) {
+        return status;
+    }
+
     return _PyStatus_OK();
 }