asyncio-wait-example.py

import asyncio
import random

async def do_it(n):
    if random.random() < 0.1:
        raise Exception('Failed test')
    await asyncio.sleep(random.uniform(0.5, 2))
    return n


async def all_completed(count):
    tasks_all = [asyncio.create_task(do_it(i), name=f'Task-{i}') for i in range(count)]
    done, pending = await asyncio.wait(
        tasks_all,
        return_when=asyncio.ALL_COMPLETED
    )
    for task in done:
        try:
            print(f"Task {task.get_name()} done: {task.result()}")
        except Exception as e:
            print(f"Task {task.get_name()} failed: {e}")


async def first_completed(count):
    tasks_all = [asyncio.create_task(do_it(i), name=f'Task-{i}') for i in range(count)]
    done, pending = await asyncio.wait(
        tasks_all,
        return_when=asyncio.FIRST_COMPLETED
    )
    for task in done:
        try:
            print(f"Task {task.get_name()} done: {task.result()}")
        except Exception as e:
            print(f"Task {task.get_name()} failed: {e}")
    for task in pending:
        task.cancel()


async def first_exception(count):
    tasks_all = [asyncio.create_task(do_it(i), name=f'Task-{i}') for i in range(count)]
    done, pending = await asyncio.wait(
        tasks_all,
        return_when=asyncio.FIRST_EXCEPTION
    )
    for task in done:
        try:
            print(f"Task {task.get_name()} done: {task.result()}")
        except Exception as e:
            print(f"Task {task.get_name()} failed: {e}")
    for task in pending:
        task.cancel()


task_count = 10

print('ALL COMPLETED')
asyncio.run(all_completed(task_count))

print('FIRST COMPLETED')
asyncio.run(first_completed(task_count))

print('FIRST EXCEPTION')
asyncio.run(first_exception(task_count))