https://github.com/python/cpython/commit/5bca7f4d7ab685802a79e50e6746173c5cd7a00a commit: 5bca7f4d7ab685802a79e50e6746173c5cd7a00a branch: 3.14 author: Miss Islington (bot) <[email protected]> committer: colesbury <[email protected]> date: 2025-11-21T18:57:30Z summary:
[3.14] gh-137422: Fix race condition in PyImport_AddModuleRef (gh-141822) (gh-141830) (cherry picked from commit 2d50dd242e04b94f86cb23c4972c1b423c670175) Co-authored-by: Sam Gross <[email protected]> files: A Lib/test/test_free_threading/test_capi.py A Misc/NEWS.d/next/C_API/2025-11-21-10-34-00.gh-issue-137422.tzZKLi.rst M Python/import.c diff --git a/Lib/test/test_free_threading/test_capi.py b/Lib/test/test_free_threading/test_capi.py new file mode 100644 index 00000000000000..146d7cfc97adb7 --- /dev/null +++ b/Lib/test/test_free_threading/test_capi.py @@ -0,0 +1,47 @@ +import ctypes +import sys +import unittest + +from test.support import threading_helper +from test.support.threading_helper import run_concurrently + + +_PyImport_AddModuleRef = ctypes.pythonapi.PyImport_AddModuleRef +_PyImport_AddModuleRef.argtypes = (ctypes.c_char_p,) +_PyImport_AddModuleRef.restype = ctypes.py_object + + +@threading_helper.requires_working_threading() +class TestImportCAPI(unittest.TestCase): + def test_pyimport_addmoduleref_thread_safe(self): + # gh-137422: Concurrent calls to PyImport_AddModuleRef with the same + # module name must return the same module object. + + NUM_ITERS = 10 + NTHREADS = 4 + + module_name = f"test_free_threading_addmoduleref_{id(self)}" + module_name_bytes = module_name.encode() + sys.modules.pop(module_name, None) + results = [] + + def worker(): + module = _PyImport_AddModuleRef(module_name_bytes) + results.append(module) + + for _ in range(NUM_ITERS): + try: + run_concurrently(worker_func=worker, nthreads=NTHREADS) + self.assertEqual(len(results), NTHREADS) + reference = results[0] + for module in results[1:]: + self.assertIs(module, reference) + self.assertIn(module_name, sys.modules) + self.assertIs(sys.modules[module_name], reference) + finally: + results.clear() + sys.modules.pop(module_name, None) + + +if __name__ == "__main__": + unittest.main() diff --git a/Misc/NEWS.d/next/C_API/2025-11-21-10-34-00.gh-issue-137422.tzZKLi.rst b/Misc/NEWS.d/next/C_API/2025-11-21-10-34-00.gh-issue-137422.tzZKLi.rst new file mode 100644 index 00000000000000..656289663cfebb --- /dev/null +++ b/Misc/NEWS.d/next/C_API/2025-11-21-10-34-00.gh-issue-137422.tzZKLi.rst @@ -0,0 +1,4 @@ +Fix :term:`free threading` race condition in +:c:func:`PyImport_AddModuleRef`. It was previously possible for two calls to +the function return two different objects, only one of which was stored in +:data:`sys.modules`. diff --git a/Python/import.c b/Python/import.c index add78534606bf0..0158709ad91947 100644 --- a/Python/import.c +++ b/Python/import.c @@ -3,6 +3,7 @@ #include "Python.h" #include "pycore_audit.h" // _PySys_Audit() #include "pycore_ceval.h" +#include "pycore_critical_section.h" // Py_BEGIN_CRITICAL_SECTION() #include "pycore_hashtable.h" // _Py_hashtable_new_full() #include "pycore_import.h" // _PyImport_BootstrapImp() #include "pycore_initconfig.h" // _PyStatus_OK() @@ -309,13 +310,8 @@ PyImport_GetModule(PyObject *name) if not, create a new one and insert it in the modules dictionary. */ static PyObject * -import_add_module(PyThreadState *tstate, PyObject *name) +import_add_module_lock_held(PyObject *modules, PyObject *name) { - PyObject *modules = get_modules_dict(tstate, false); - if (modules == NULL) { - return NULL; - } - PyObject *m; if (PyMapping_GetOptionalItem(modules, name, &m) < 0) { return NULL; @@ -335,6 +331,21 @@ import_add_module(PyThreadState *tstate, PyObject *name) return m; } +static PyObject * +import_add_module(PyThreadState *tstate, PyObject *name) +{ + PyObject *modules = get_modules_dict(tstate, false); + if (modules == NULL) { + return NULL; + } + + PyObject *m; + Py_BEGIN_CRITICAL_SECTION(modules); + m = import_add_module_lock_held(modules, name); + Py_END_CRITICAL_SECTION(); + return m; +} + PyObject * PyImport_AddModuleRef(const char *name) { _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
