Delete state of new thread on its startup failure

If Python fails to start newly created thread due to failure of underlying PyThread_start_new_thread() call, its state should be removed from interpreter' thread states list to avoid its double cleanup * make 'PyThreadState_Delete' accept unbound thread state * in 'thread_PyThread_start_new_thread', delete state of new thread from interpreter if 'PyThread_start_new_thread' call fails
serhiy-storchaka · Nov 22, 2024 · Sep 22, 2023 · Sep 22, 2023 · Sep 23, 2023 · Sep 23, 2023
commit 788b0b6c8c85eb8e9037b306e92078d218450c39
diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
@@ -1045,6 +1045,26 @@ def exit_handler():
         self.assertEqual(out, b'')
         self.assertIn(b"can't create new thread at interpreter shutdown", err)
 
+    def test_start_new_thread_failed(self):
+        # gh-109746: if Python fails to start newly created thread
+        # due to failure of underlying PyThread_start_new_thread() call,
+        # its state should be removed from interpreter' thread states list
+        # to avoid its double cleanup
+        code = """if 1:
+            import resource
+            import threading
+
+            resource.setrlimit(resource.RLIMIT_NPROC, (150, 150))
+
+            while True:
+                t = threading.Thread()
+                t.start()
+                t.join()
+        """
+        _, out, err = assert_python_failure("-c", code)
+        self.assertEqual(out, b'')
+        self.assertIn(b"can't start new thread", err)
+
 class ThreadJoinOnShutdown(BaseTestCase):
 
     def _run_and_join(self, script):

diff --git a/Modules/_threadmodule.c b/Modules/_threadmodule.c
@@ -1204,6 +1204,7 @@ thread_PyThread_start_new_thread(PyObject *self, PyObject *fargs)
     if (ident == PYTHREAD_INVALID_THREAD_ID) {
         PyErr_SetString(ThreadError, "can't start new thread");
         PyThreadState_Clear(boot->tstate);
+        PyThreadState_Delete(boot->tstate);
         thread_bootstate_free(boot, 1);
         return NULL;
     }

@@ -1589,7 +1589,9 @@ tstate_delete_common(PyThreadState *tstate)
     if (tstate->_status.bound_gilstate) {
         unbind_gilstate_tstate(tstate);
     }
-    unbind_tstate(tstate);
+    if (tstate->_status.bound) {
+        unbind_tstate(tstate);
+    }
 
     // XXX Move to PyThreadState_Clear()?
     clear_datastack(tstate);