How to shutdown the loop and print error if coroutine raised an exception with asyncio?

Question

Suppose I have a few coroutines running in a loop. How to make so that if some of them failed with exception the whole program would fail with this exception? Because right now asyncio doesn't even prints the error messages from coroutines unless I use logging level "DEBUG".

from asyncio import get_event_loop, sleep


async def c(sleep_time=2, fail=False):
    print('c', sleep_time, fail)
    if fail:
        raise Exception('fail')
    while True:
        print('doing stuff')
        await sleep(sleep_time)



loop = get_event_loop()
loop.create_task(c(sleep_time=10, fail=False))
loop.create_task(c(fail=True))
loop.run_forever()

Answer 1

A graceful way is using error handling api.

https://docs.python.org/3/library/asyncio-eventloop.html#error-handling-api

Example:

import asyncio


async def run_division(a, b):
    await asyncio.sleep(2)
    return a / b


def custom_exception_handler(loop, context):
    # first, handle with default handler
    loop.default_exception_handler(context)

    exception = context.get('exception')
    if isinstance(exception, ZeroDivisionError):
        print(context)
        loop.stop()

loop = asyncio.get_event_loop()

# Set custom handler
loop.set_exception_handler(custom_exception_handler)
loop.create_task(run_division(1, 0))
loop.run_forever()