[3.13] gh-120524: Avoid a Race On _PyRuntime.types.managed_static.types[i].interp_cou...

gh-120182 added new global state (interp_count), but didn't add thread-safety for it.  This change eliminates the possible race.

(cherry picked from commit 2c66318cdc0545da37e7046533dfe74bde129d91, AKA gh-120529)

Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>

diff --git a/Lib/test/test_interpreters/test_stress.py b/Lib/test/test_interpreters/test_stress.py
index 40d2d77a7b9d3e2b19763ef6895a6327b5ede72a..e400535b2a0e4ef0f14f02f7f8e92df4135d263a 100644 (file)
--- a/Lib/test/test_interpreters/test_stress.py
+++ b/Lib/test/test_interpreters/test_stress.py
@@ -22,7 +22,6 @@ class StressTests(TestBase):
             interp = interpreters.create()
             alive.append(interp)
 
-    @unittest.skip('(temporary) gh-120524: there is a race that needs fixing')
     @support.requires_resource('cpu')
     def test_create_many_threaded(self):
         alive = []

diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 1123ef6eb3d9b2b2d6944edfdfbdf81d85e04b04..5c490e833739fc8f20856ea4293f265ee2b30455 100644 (file)
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -246,7 +246,8 @@ managed_static_type_state_init(PyInterpreterState *interp, PyTypeObject *self,
 
     assert((initial == 1) ==
             (_PyRuntime.types.managed_static.types[full_index].interp_count == 0));
-    _PyRuntime.types.managed_static.types[full_index].interp_count += 1;
+    (void)_Py_atomic_add_int64(
+            &_PyRuntime.types.managed_static.types[full_index].interp_count, 1);
 
     if (initial) {
         assert(_PyRuntime.types.managed_static.types[full_index].type == NULL);
@@ -300,7 +301,8 @@ managed_static_type_state_clear(PyInterpreterState *interp, PyTypeObject *self,
     state->type = NULL;
     assert(state->tp_weaklist == NULL);  // It was already cleared out.
 
-    _PyRuntime.types.managed_static.types[full_index].interp_count -= 1;
+    (void)_Py_atomic_add_int64(
+            &_PyRuntime.types.managed_static.types[full_index].interp_count, -1);
     if (final) {
         assert(!_PyRuntime.types.managed_static.types[full_index].interp_count);
         _PyRuntime.types.managed_static.types[full_index].type = NULL;