Python - asyncio - 从未检索到任务异常

Question

说明:(简体)

我有2个任务。

在每个任务中，我有 3 个协程。

第一个任务的 2 个协程失败。 (模拟)

在处理任务结果时，我收到一条“从未检索到任务异常”消息。

我相信这是因为仅处理了该任务中两个失败的协程之一的异常。

如何处理任务中两个协程的异常和/或避免“从未检索到任务异常”消息？

代码:(简体)

import asyncio
async def download(data):
    filename = "*" if data in ["b", "c"] else data  # simulated failure
    with open(filename, "w") as f:
        f.write(data)
async def coro(data_list):
    coroutines = [download(data) for data in data_list]
    for coroutine in asyncio.as_completed(coroutines):
        await coroutine
async def main():
    task1 = asyncio.create_task(coro(["a", "b", "c"]))
    task2 = asyncio.create_task(coro(["d", "e", "f"]))
    results = await asyncio.gather(task1, task2, return_exceptions=True)
    for _ in results:
        pass
asyncio.run(main())

输出:(简化)

Task exception was never retrieved
future: <Task finished coro=<download() done, defined at D:/myscript.py:2> exception=OSError(22, 'Invalid argument')>
Traceback (most recent call last):
  File "D:/myscript.py", line 4, in download
    with open(filename, "w") as f:
OSError: [Errno 22] Invalid argument: '*'

Answer 1

如果你想收集异常而不是引发它们，你可以使用 asyncio.gather(return_exceptions=True)在 coro以及。例如:

import asyncio

async def download(data):
    if data in ['b', 'c']:
        1/0    # simulate error
    return 42  # success

async def coro(data_list):
    coroutines = [download(data) for data in data_list]
    return await asyncio.gather(*coroutines, return_exceptions=True)

async def main():
    task1 = asyncio.create_task(coro(["a", "b", "c"]))
    task2 = asyncio.create_task(coro(["d", "e", "f"]))
    return await asyncio.gather(task1, task2, return_exceptions=True)

print(asyncio.run(main()))

这将打印:

[[42, ZeroDivisionError('division by zero'), ZeroDivisionError('division by zero')], [42, 42, 42]]