Celery warm shutdown solo taskpool

tasks.py

import asyncio
import time

from celery import Celery


app = Celery('tasks')


class TaskBackend:
    async def __aenter__(self):
        self.process = await asyncio.create_subprocess_exec(
            'celery', 'worker', '--app', 'tasks',
            '--concurrency', '1',
            '--pool', 'solo',
        )

    async def __aexit__(self, exc_type, exc, tb):
        self.process.terminate()
        await self.process.wait()


@app.task
def mytask():
    print('starting...')
    time.sleep(5)
    print('done')


async def test():
    async with TaskBackend():
        mytask.delay()
        await asyncio.sleep(3)


if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    loop.run_until_complete(test())