处理 Python 事件循环关闭，无异常

#! /usr/bin/env python3

from asyncio import gather, get_event_loop, sleep, Event
from signal import SIGINT, SIGTERM


def shutdown_signaled():
    print('Shutdown requested.')
    shutdown.set()


async def small_work(shutdown):
    while not shutdown.is_set():
        await sleep(0.5)
        print('Small work is done!')

    print('Exited small work.')


async def big_work(shutdown):
    while not shutdown.is_set():
        await sleep(5)
        print('Big work is done!!!')

    print('Exited big work.')


# when this event is set the application is ready to shutdown
shutdown = Event()

# setting up our own handler for Ctrl+C and SIGTERM (sent with kill)
# by setting this handler running tasks will not get an exception thrown at them
event_loop = get_event_loop()
event_loop.add_signal_handler(SIGINT, shutdown_signaled)
event_loop.add_signal_handler(SIGTERM, shutdown_signaled)

# combining our two tasks as one
combined_tasks = gather(small_work(shutdown), big_work(shutdown))

# run our tasks and block
event_loop.run_until_complete(combined_tasks)