如何在后台运行任务时从异步 function 返回值？

Question

[edit] Python 3.6

There is a function:

def main(request):
    do_something() // task takes some days
    responce = {'status': 'started!'}
    return responce

I need it to return a responce right after do_something() started and NOT waiting for do_something() to be finished. I have already tried this:

def main(request):
    Thread(target=do_something).start()
    responce = {'status': 'started!'}
    return responce

It works only if do_something() doesn't contain threads inside. Please, help with the usage of async-await here 'without extra code lines'

[update] this works fine only in Jupyter, but not in docker container(there yields 'RuntimeError: There is no current event loop in thread'):

import asyncio

async def do_something():
    print("internal training started")
    await asyncio.sleep(5)
    print("internal training finished")

def main():
    asyncio.ensure_future(train_models())
    responce = {'status': 'started!'}
    return responce
print(main())

[update] the problem was not with threads ans asynchronous functions, the problem was with azure-functions. [closed]

Answer 1

Using asyncio :

import asyncio


async def do_something():
    for i in range(10):
        print(f"Been doing expensive stuff for {i} seconds.")
        await asyncio.sleep(1)


def handle_request(request):
    task = asyncio.create_task(do_something())
    response = {request: {"status": "started!"}}
    return response, task


async def main():
    response, task = handle_request("request")
    print(response)
    await task
    print("Program finished.")


if __name__ == "__main__":
    asyncio.run(main())

Output:

 {'request': {'status': 'started.'}} Been doing expensive stuff for 0 seconds. Been doing expensive stuff for 1 seconds. Been doing expensive stuff for 2 seconds. Been doing expensive stuff for 3 seconds. Been doing expensive stuff for 4 seconds. Been doing expensive stuff for 5 seconds. Been doing expensive stuff for 6 seconds. Been doing expensive stuff for 7 seconds. Been doing expensive stuff for 8 seconds. Been doing expensive stuff for 9 seconds. Program finished.

Or alternatively using threading :

import time
from threading import Thread


def do_something():
    for i in range(10):
        print(f"Been doing expensive stuff for {i} seconds.")
        time.sleep(1)


def handle_request(request):
    thread = Thread(target=do_something)
    thread.start()
    response = {request: {"status": "started!"}}
    return response, thread


def main():
    response, thread = handle_request("request")
    print(response)
    thread.join()
    print("Program finished.")


if __name__ == "__main__":
    main()

Output:

 Been doing expensive stuff for 0 seconds. {'request': {'status': 'started.'}} Been doing expensive stuff for 1 seconds. Been doing expensive stuff for 2 seconds. Been doing expensive stuff for 3 seconds. Been doing expensive stuff for 4 seconds. Been doing expensive stuff for 5 seconds. Been doing expensive stuff for 6 seconds. Been doing expensive stuff for 7 seconds. Been doing expensive stuff for 8 seconds. Been doing expensive stuff for 9 seconds. Program finished.