fix thread safety

Lib/test/test_asyncio/test_free_threading.py

@@ -0,0 +1,26 @@
+import asyncio
+from test.support import threading_helper
+from unittest import TestCase
+from threading import Thread
+
+threading_helper.requires_working_threading(module=True)
+
+class TestFreeThreading(TestCase):
+    def test_all_tasks_race(self) -> None:
+        async def task():
+            await asyncio.sleep(0)
+
+        async def main():
+            async with asyncio.TaskGroup() as tg:
+                for _ in range(100):
+                    tg.create_task(task())
+                    asyncio.all_tasks()
+
+        threads = []
+        for _ in range(10):
+            thread = Thread(target=lambda: asyncio.run(main()))
+            threads.append(thread)
+
+        with threading_helper.start_threads(threads):
+            pass
+