从未等待过 python asyncio 协程

Question

I am using python 3.8 with this code

async def main():
    pass

async def build():
    pass

asyncio.create_task(build())
loop = asyncio.get_event_loop()
asyncio.create_task(main())
pending = asyncio.all_tasks()
loop.run_until_complete(asyncio.gather(*pending))

and get the following error

sys:1: RuntimeWarning: coroutine 'build' was never awaited

What am I missing here? shouldn't run until complete wait for all the tasks to finish?

Answer 1

As the loop is not running when creating the task, asyncio is unable to attach tasks to it.

This can be fixed by replacing asyncio.create_task() with loop.create_task() .

The full error can be retrieved using asyncio.gather(..., return_exceptions=True) so gather() will raise a RuntimeError: no running event loop .