[3.11] GH-98543: Fix asyncio.TaskGroup to not keep reference to errors after raising ExceptionGroup (GH-98544) (#98550)

miss-islington · kumaraditya303 · web-flow · commit 36d25a4f7f82 · 2022-10-24T11:08:22.000-07:00
GH-98543: Fix `asyncio.TaskGroup` to not keep reference to errors after raising ExceptionGroup (GH-98544) (cherry picked from commit f4a1494) Co-authored-by: Kumar Aditya <59607654+kumaraditya303@users.noreply.github.com>
diff --git a/Lib/asyncio/taskgroups.py b/Lib/asyncio/taskgroups.py
@@ -128,11 +128,11 @@ async def __aexit__(self, et, exc, tb):
             # Exceptions are heavy objects that can have object
             # cycles (bad for GC); let's not keep a reference to
             # a bunch of them.
-            errors = self._errors
-            self._errors = None
-
-            me = BaseExceptionGroup('unhandled errors in a TaskGroup', errors)
-            raise me from None
+            try:
+                me = BaseExceptionGroup('unhandled errors in a TaskGroup', self._errors)
+                raise me from None
+            finally:
+                self._errors = None
 
     def create_task(self, coro, *, name=None, context=None):
         if not self._entered:
