只能通过继承在进程之间共享获取队列对象，但我没有使用队列

问题描述

我正在尝试使用ProcessPoolExecutor，但收到错误"队列对象应仅通过继承在进程之间共享"，但我没有使用队列(至少没有显式使用)。我找不到任何东西来解释我做错了什么。

以下是演示该问题的一些代码(不是我的实际代码)：

from concurrent.futures import ProcessPoolExecutor, as_completed

class WhyDoesntThisWork:

    def __init__(self):
        self.executor = ProcessPoolExecutor(4)

    def execute_something(self, starting_letter):
        futures = [self.executor.submit(self.something, starting_letter, d) for d in range(4)]
        letter = None
        for future in as_completed(futures):
            letter = future.result()
        print(letter)

    def something(self, letter, d):
        # do something pointless for the example
        for x in range(d):
            letter = chr(ord(letter) + 1)

if __name__ == '__main__':
    WhyDoesntThisWork(). execute_something('A')

El Ruso曾指出，将某事()设为静态方法或类方法可以消除错误。遗憾的是，我的实际代码需要使用self调用其他方法。

---

解决方案

尝试something

的代码

@staticmethod
def something(letter, d):
    # do something pointless for the example
    for x in range(d):
        letter = chr(ord(letter) + 1)

或重构为：

from concurrent.futures import ProcessPoolExecutor, as_completed


class WhyDoesntThisWork:
    def something(self, letter, d):
        # do something pointless for the example
        for x in range(d):
            letter = chr(ord(letter) + 1)
        return letter


if __name__ == '__main__':
    executor = ProcessPoolExecutor(4)
    letter = 'A'
    obj = WhyDoesntThisWork()
    futures = [executor.submit(obj.something, letter, d) for d in range(4)]
    for future in as_completed(futures):
        print(future.result())