bpo-35125: remove inner callback on outer cancellation in asyncio shield (GH-10340)
When the future returned by shield is cancelled, its completion callback of the
inner future is not removed. This makes the callback list of inner inner future
grow each time a shield is created and cancelled.
This change unregisters the callback from the inner future when the outer
future is cancelled.
https://bugs.python.org/issue35125
(cherry picked from commit b35acc5b3a0148c5fd4462968b310fb436726d5a)
Co-authored-by: Romain Picard <romain.picard@oakbits.com>
diff --git a/Lib/asyncio/tasks.py b/Lib/asyncio/tasks.py
index 2af4f32..402c6e2 100644
--- a/Lib/asyncio/tasks.py
+++ b/Lib/asyncio/tasks.py
@@ -774,7 +774,7 @@
loop = futures._get_loop(inner)
outer = loop.create_future()
- def _done_callback(inner):
+ def _inner_done_callback(inner):
if outer.cancelled():
if not inner.cancelled():
# Mark inner's result as retrieved.
@@ -790,7 +790,13 @@
else:
outer.set_result(inner.result())
- inner.add_done_callback(_done_callback)
+
+ def _outer_done_callback(outer):
+ if not inner.done():
+ inner.remove_done_callback(_inner_done_callback)
+
+ inner.add_done_callback(_inner_done_callback)
+ outer.add_done_callback(_outer_done_callback)
return outer