import asyncio


async def gen():
    _ = [1] * 100000  # a large object
    yield
    yield 666
    print('func returned!')
    # "666" can't be yielded, so the function will never return.


async def loop():
    q = gen()
    await q.__anext__()
    await q.asend(123456)
    # "q" should be cleaned by GC, and return the memory back to system,
    # but actually not.


async def main():
    for _ in range(1000):
        await loop()
    input()  # check the memory usage, Python uses about 700MiB+ memory,.


asyncio.run(main())