I’m trying to asyncio.create_task()
but I’m dealing with this error:
Here’s an example:
import asyncio import time async def async_say(delay, msg): await asyncio.sleep(delay) print(msg) async def main(): task1 = asyncio.create_task(async_say(4, 'hello')) task2 = asyncio.create_task(async_say(6, 'world')) print(f"started at {time.strftime('%X')}") await task1 await task2 print(f"finished at {time.strftime('%X')}") loop = asyncio.get_event_loop() loop.run_until_complete(main())
Out:
AttributeError: module 'asyncio' has no attribute 'create_task'
So I tried with the following code snippet (.ensure_future()
) instead, without any problem:
async def main(): task1 = asyncio.ensure_future(async_say(4, 'hello')) task2 = asyncio.ensure_future(async_say(6, 'world')) print(f"started at {time.strftime('%X')}") await task1 await task2 print(f"finished at {time.strftime('%X')}") loop = asyncio.get_event_loop() loop.run_until_complete(main())
Out:
started at 13:19:44 hello world finished at 13:19:50
What’s wrong?
[NOTE]:
- Python 3.6
- Ubuntu 16.04
[UPDATE]:
With borrowing from @user4815162342 Answer, my problem solved:
async def main(): loop = asyncio.get_event_loop() task1 = loop.create_task(async_say(4, 'hello')) task2 = loop.create_task(async_say(6, 'world')) print(f"started at {time.strftime('%X')}") await task1 await task2 print(f"finished at {time.strftime('%X')}") loop = asyncio.get_event_loop() loop.run_until_complete(main())
Advertisement
Answer
The create_task
top-level function was added in Python 3.7, and you are using Python 3.6. Prior to 3.7, create_task
was only available as a method on the event loop, so you can invoke it like that:
async def main(): loop = asyncio.get_event_loop() task1 = loop.create_task(async_say(4, 'hello')) task2 = loop.create_task(async_say(6, 'world')) # ... await task1 await task2
That works in both 3.6 and 3.7, as well as in earlier versions. asyncio.ensure_future
will work as well, but when you know you’re dealing with a coroutine, create_task
is more explicit and is the preferred option.