Nested finalisation handled differently from Trio

Thank you for this excellent library. I noticed that tasks created in nested groups do not appear to be finalised when their group is cancelled. The tests below illustrate the problem. The Trio version passes.

anyio == 1.4.0 trio == 0.16.0

import pytest
import anyio
import trio


@pytest.mark.anyio
async def test_anyio():
    async def subtask(finalised):
        try:
            await anyio.sleep(999)
        finally:
            # *** Not called ***
            await finalised.set()

    async def subgroup(finalised):
        async with anyio.create_task_group() as tg:
            await tg.spawn(subtask, finalised)

    async def main():
        finalised = anyio.create_event()
        async with anyio.create_task_group() as tg:
            await tg.spawn(subgroup, finalised)
            await anyio.sleep(1)
            await tg.cancel_scope.cancel()
        assert finalised.is_set()

    await main()


@pytest.mark.trio
async def test_trio():
    async def subtask(finalised):
        try:
            await trio.sleep(999)
        finally:
            finalised.set()

    async def subgroup(finalised):
        async with trio.open_nursery() as n:
            n.start_soon(subtask, finalised)

    async def main():
        finalised = trio.Event()
        async with trio.open_nursery() as n:
            n.start_soon(subgroup, finalised)
            await trio.sleep(1)
            n.cancel_scope.cancel()
        assert finalised.is_set()

    await main()

FAILED test.py::test_anyio[asyncio] - assert False

[agronholm]

I will check this out. Your timing is pretty good because I’m currently in the middle of a major push for AnyIO v2.0 and if any semantics need to be changed, this would be the perfect opportunity for that.

[mjwestcott]

Thanks, but I can wait for v2.0. I’m building a stream processing library on top of AnyIO, still in the early stages of development.