尝试生成多个进程时出现运行时错误（图像检测和打印到终端）

Question

我正在按照 this 指南尝试查看是否可以获得一个简单的多处理脚本运行。在其他问题中已经讨论过我需要使用多处理来实现我想要实现的目标。

为了跟上新手指南，我写了两个函数。

import pyautogui as py
import multiprocessing

def print_i():
    for i in range(0, 21):
        print(i)
        sleep(0.1)

image = r'C:\Users\image.jpg'

def closeWindow():
    while True:
        found = py.locateCenterOnScreen(image)
            if found != None:
            py.click(1797, 134)

print_i 打印出数字 0-20，closeWindow 检查特定的 window 是否打开，如果找到则单击关闭它，两者都单独工作。

按照指南，我导入了 multiprocessing 并完成了以下操作：

p1 = multiprocessing.Process(target= print_i)
p2 = multiprocessing.Process(target= closeWindow)

p1.start()
p2.start()

p1.join()
p2.join()

但是，我立即收到两次以下错误：

RuntimeError:
        An attempt has been made to start a new process before the
        current process has finished its bootstrapping phase.

        This probably means that you are not using fork to start your
        child processes and you have forgotten to use the proper idiom
        in the main module:

            if __name__ == '__main__':
                freeze_support()
                ...

        The "freeze_support()" line can be omitted if the program
        is not going to be frozen to produce an executable.

This stack 解释说，多处理模块应该处理这些情况，并检测到您正在尝试启动新进程，甚至在目标运行.

之前

在阅读提到不使用 fork 启动子进程的错误时，我认为我没有子进程，在多处理时，第一个进程之后的任何东西都算作子进程吗？如果是，如何在运行同时进行图像检测的同时用一个过程输出数字0-20？

Answer 1

有很多方法可以连续安排或运行任务。这里有几个例子：

使用线程：

from threading import Thread
from time import sleep

def run_close_window_task():
    while True:
        print("Hello, close window task is running!")
        sleep(2)

t = Thread(name='backgroundtask', target=run_close_window_task)
t.start()

print("Now we are doing other stuff, while the other task is running...")

注意：您必须在 Windows 中通过任务管理器终止 Python 进程才能停止它。

结果：

Hello, close window task is running!
Now we are doing other stuff, while the other task is running...
Hello, close window task is running!
Hello, close window task is running!
Hello, close window task is running!
...

使用 Asyncio：

from asyncio import sleep, run, create_task, gather

async def run_close_window_task():
    while True:
        print("Hello, close window task is running!")
        await sleep(2)

async def print_i():
    while True:
        for i in range(0, 21):
            print(f"Printing i: {str(i)}")
            await sleep(0.2)

async def main():
    tasks = [create_task(run_close_window_task()), create_task(print_i())]
    await gather(*tasks, return_exceptions=False)

if __name__ == "__main__":
    run(main())

结果：

Hello, close window task is running!
Printing i: 0
Printing i: 1
Printing i: 2
Printing i: 3
Printing i: 4
Printing i: 5
Printing i: 6
Printing i: 7
Printing i: 8
Printing i: 9
Hello, close window task is running!
Printing i: 10
Printing i: 11
Printing i: 12
Printing i: 13
Printing i: 14
Printing i: 15
Printing i: 16
Printing i: 17
Printing i: 18
Printing i: 19
...

尝试生成多个进程时出现运行时错误（图像检测和打印到终端）

Runtime error when trying to spawn multiple processes (image detection and print to terminal)

python

multiprocessing