asyncio.create_task 装饰器不会同时执行

Question

I have having some trouble understanding asyncio's create_task function. From the documentation, tasks should be run concurrently when they are awaited. I wrapped the async func in a deocrator so I don't have to create_task() for every async function. But the concurrent execution fails

  import asyncio
  import time


  def async_task(func):
      def wrapper():
          return asyncio.create_task(func())
      return wrapper


  @async_task
  async def bar() -> int:
      await asyncio.sleep(3)
      return "hello"


  @async_task
  async def foo() -> int:
      await asyncio.sleep(3)
      return "world"


  async def main() -> None:
      print(time.strftime('%X'))
      print(await bar())
      print(await foo())
      print(time.strftime('%X'))

  asyncio.run(main())

Answer 1

There's a difference between:

asyncio.create_task(async_fun())

and

await asyncio.create_task(async_fun())

The second one waits for the task to finish before going forward, so you're scheduling foo only after bar has finished.

First create tasks then await for them:

foo_task = foo()
bar_task = bar()
await foo_task
await bar_task

Or use asyncio.gather

await asyncio.gather(foo(), bar())