swap the stream contexts with the taskgroup context

        with send_channel, receive_channel:
            async with anyio.create_task_group() as task_group:

might be better as

        async with anyio.create_task_group() as task_group:
            with send_channel, receive_channel:

this way closing the amap context manager (None, None, None)ly would allow currently running tasks to finish, and prevent new tasks being added. Closing the amap context manager (type[T], T, tb)ly would still cancel all tasks

[graingert]

@florimondmanca looking for a soft-cancel approach for @pfmoore here https://github.com/agronholm/anyio/discussions/333#discussioncomment-960478

[graingert]

also anyio 3 supports taskgroup.start so you can limit tasks with:

async def execute_task(semaphore, async_fn, \, *args, task_status, **kwargs):
    async with semaphore:
        task_status.started()
        await async_fn(*args, **kwargs)

async with anyio.create_task_group() as tg:
    for task in tasks:
        await tg.start(execute_task, task, semaphore)