如何取消使用`concurrent.futures.ProcessPoolExecutor`运行的长时间运行的子进程？

Question

你可以看到完整的here。

我的代码的简化版本如下：

executor = ProcessPoolExecutor(10)
try:
    coro = bot.loop.run_in_executor(executor, processUserInput, userInput)
    result = await asyncio.wait_for(coro, timeout=10.0, loop=bot.loop)
except asyncio.TimeoutError:
    result="Operation took longer than 10 seconds. Aborted."

不幸的是，当操作超时时，该进程仍在运行，即使未来已被取消。如何取消该进程/任务以使其真正停止运行？

Answer 1

ProcessPoolExecutor 使用multiprocessing 模块。与其取消不.terminate()子进程的事件，不如使用multiprocessing.Event让你的子进程正常退出：

import asyncio
import multiprocessing
import time
from concurrent.futures.process import ProcessPoolExecutor


def f(done):
    print("hi")

    while not done.is_set():
        time.sleep(1)
        print(".")

    print("bye")

    return 12345


async def main():
    done = manager.Event()
    fut = loop.run_in_executor(None, f, done)
    print("waiting...")
    try:
        result = await asyncio.wait_for(asyncio.shield(fut), timeout=3)
    except asyncio.TimeoutError:
        print("timeout, exiting")
        done.set()
        result = await fut
    print("got", result)

loop = asyncio.get_event_loop()
loop.set_default_executor(ProcessPoolExecutor())
manager = multiprocessing.Manager()

loop.run_until_complete(main())