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I'm a little bit confused by some asyncio functions. I see there is BaseEventLoop.create_task(coro) function to schedule a co-routine. The documentation for create_task says its a new function and for compatibility we should use asyncio.async(coro) which by referring to docs again I see is an alias for asyncio.ensure_future(coro) which again schedules the execution of a co-routine.

Meanwhile, I've been using Task(coro) for scheduling co-routine execution and that too seems to be working fine. so, what's the difference between all these?

As you've noticed, they all do the same thing.

asyncio.async had to be replaced with asyncio.ensure_future because in Python >= 3.5, async has been made a keyword[1].

create_task's raison d'etre[2]:

Third-party event loops can use their own subclass of Task for interoperability. In this case, the result type is a subclass of Task.

And this also means you should not create a Task directly, because different event loops might have different ways of creating a "Task".


Another important difference is that in addition to accepting coroutines, ensure_future also accepts any awaitable object; create_task on the other hand just accepts coroutines.

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    • This was counter-intuitive because it sounded like you said to use ensure_future and not create_task, so I made my research. In 2016, Guido said the opposite. If you know you have a coroutine and you want to schedule its execution, you should just call create_task directly. create_task exists so a third party loop can return a subclass so you shouldn't call the task constructor directly. Hope that clears things up for other asyncio neophytes.

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