Python: asynchronous generator is already running

Question

As in the following example, I encountered an unusual error when using async Generator.

async def demo():
    async def get_data():
        for i in range(5):  # loop: for or while
            await asyncio.sleep(1)  # some IO code

            yield i

    datas = get_data()

    await asyncio.gather(
        anext(datas),
        anext(datas),
        anext(datas),
        anext(datas),
        anext(datas),
    )


if __name__ == '__main__':
    # asyncio.run(main())
    asyncio.run(demo())

Console output:

2022-05-11 23:55:24,530 DEBUG asyncio 29180 30600 Using proactor: IocpProactor
Traceback (most recent call last):
  File "E:\workspace\develop\python\crawlerstack-proxypool\demo.py", line 77, in <module>
    asyncio.run(demo())
  File "D:\devtools\Python310\lib\asyncio\runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "D:\devtools\Python310\lib\asyncio\base_events.py", line 641, in run_until_complete
    return future.result()
  File "E:\workspace\develop\python\crawlerstack-proxypool\demo.py", line 66, in demo
    await asyncio.gather(
RuntimeError: anext(): asynchronous generator is already running

Situation description: I have a loop logic that fetches a batch of data from Redis at a time, and I want to use yield to return the result. But this error occurs when I create a concurrent task.

Is there a good solution to this situation? I don't mean to change the way I'm using it now, but to see if I can tell if it's running or something like a lock and wait for it to run and then execute anext.

Maybe my logic is not reasonable now, but I also want to understand some critical language, let me realize the seriousness of this.

Thank you for your help.