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TaskGroup fails to cancel tasks pending creation, if that task starts a failing task #128550
Description
Bug report
Bug description:
this 'deadlocks' on eager tasks, but raises an EG as expected on regular 'lazy' tasks.
import sys
import asyncio
if sys.version_info >= (3, 13):
from asyncio import EventLoop
elif sys.platform == "win32":
from asyncio import ProactorEventLoop as EventLoop
else:
from asyncio import SelectorEventLoop as EventLoop
def loop_factory():
loop = EventLoop()
loop.set_task_factory(asyncio.eager_task_factory)
return loop
async def main():
async with asyncio.TaskGroup() as tg:
async def third_task():
raise RuntimeError("third task failed")
async def second_task():
tg.create_task(third_task())
await asyncio.Event().wait()
tg.create_task(second_task())
# asyncio.run(main())
asyncio.run(main(), loop_factory=loop_factory)CPython versions tested on:
3.12, 3.13, 3.14
Operating systems tested on:
Linux
Activity
pythongh-128550: TaskGroup: cancel tasks added to set after aborting
pythongh-128550: TaskGroup: cancel tasks added to set after aborting
kumaraditya303 commentedon Jan 20, 2025
This is happening because as per the following code, we skip scheduling the done callback to the event loop incase the task completes eagerly, I would lean towards fixing this by removing this case and always add the done callback which would be simpler and fix this.
cpython/Lib/asyncio/taskgroups.py
Lines 200 to 207 in a30277a
graingert commentedon Jan 20, 2025
@kumaraditya303 do we want this removed on 3.14, 3.13 and 3.12? or just 3.12?
kumaraditya303 commentedon Jan 20, 2025
Yes, all the branches.
graingert commentedon Jan 20, 2025
ok will get that setup,
pythongh-128550: remove problematic optimization
pythongh-128588: pythongh-128550: remove eager tasks optimization tha…
pythongh-128588: pythongh-128550: remove eager tasks optimization tha…
graingert commentedon Jan 20, 2025
ok working on news now, looks like it will fix #128588 also
gh-128588: gh-128550: remove eager tasks optimization that missed and…
pythongh-128588: pythongh-128550: remove eager tasks optimization tha…
[3.13] gh-128588: gh-128550: remove eager tasks optimization that mis…
pythongh-128588: pythongh-128550: remove eager tasks optimization tha…
pythongh-128588: pythongh-128550: remove eager tasks optimization tha…