使用asyncio

Question

我有这种情况，其中协同程序依赖于其他协同程序。如果在给定的依赖关系中发生异常，则所有依赖项应该停止并记录回溯。但是，由于重新引发了异常，因此回溯越来越长。

# coding: utf-8

import asyncio
import traceback

async def resource():
    return 7 / 0

async def worker(dependency):
    print('waiting on a dependency')

    try:
        await dependency
    except Exception as e:
        print('Worker crashed:\n' + traceback.format_exc())


async def main(loop):
    dependency = loop.create_task(resource())

    workers = [loop.create_task(worker(dependency)) for _ in range(4)]

    return await asyncio.wait(workers, loop=loop)


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

    loop.stop()
    loop.close()

对于第一次运行，回溯是这样的：

waiting on a dependency
Worker crashed:
Traceback (most recent call last):
  File "/home/slapec/scripts/sandbox/exc.py", line 13, in worker
    await dependency
  File "/home/slapec/.pyenv/versions/3.5.1/lib/python3.5/asyncio/futures.py", line 360, in __iter__
    return self.result()  # May raise too.
  File "/home/slapec/.pyenv/versions/3.5.1/lib/python3.5/asyncio/futures.py", line 274, in result
    raise self._exception
  File "/home/slapec/.pyenv/versions/3.5.1/lib/python3.5/asyncio/tasks.py", line 239, in _step
    result = coro.send(None)
  File "/home/slapec/scripts/sandbox/exc.py", line 7, in resource
    return 7 / 0
ZeroDivisionError: division by zero

第4次迭代后，就像这样：

    waiting on a dependency
Worker crashed:
Traceback (most recent call last):
  File "/home/slapec/scripts/sandbox/exc.py", line 13, in worker
    await dependency
  File "/home/slapec/.pyenv/versions/3.5.1/lib/python3.5/asyncio/futures.py", line 360, in __iter__
    return self.result()  # May raise too.
  File "/home/slapec/.pyenv/versions/3.5.1/lib/python3.5/asyncio/futures.py", line 274, in result
    raise self._exception
  File "/home/slapec/scripts/sandbox/exc.py", line 13, in worker
    await dependency
  File "/home/slapec/.pyenv/versions/3.5.1/lib/python3.5/asyncio/futures.py", line 360, in __iter__
    return self.result()  # May raise too.
  File "/home/slapec/.pyenv/versions/3.5.1/lib/python3.5/asyncio/futures.py", line 274, in result
    raise self._exception
  File "/home/slapec/scripts/sandbox/exc.py", line 13, in worker
    await dependency
  File "/home/slapec/.pyenv/versions/3.5.1/lib/python3.5/asyncio/futures.py", line 360, in __iter__
    return self.result()  # May raise too.
  File "/home/slapec/.pyenv/versions/3.5.1/lib/python3.5/asyncio/futures.py", line 274, in result
    raise self._exception
  File "/home/slapec/scripts/sandbox/exc.py", line 13, in worker
    await dependency
  File "/home/slapec/.pyenv/versions/3.5.1/lib/python3.5/asyncio/futures.py", line 360, in __iter__
    return self.result()  # May raise too.
  File "/home/slapec/.pyenv/versions/3.5.1/lib/python3.5/asyncio/futures.py", line 274, in result
    raise self._exception
  File "/home/slapec/.pyenv/versions/3.5.1/lib/python3.5/asyncio/tasks.py", line 239, in _step
    result = coro.send(None)
  File "/home/slapec/scripts/sandbox/exc.py", line 7, in resource
    return 7 / 0
ZeroDivisionError: division by zero

AFAIK它并不是特定于asyncio，但我以前从未见过这种行为。

你知道如何保留原始的追溯吗？我有一种感觉，堆栈帧也被存储，所以长时间运行的循环会占用我所有的记忆。