Python 多处理："self."变量未更新in/by其他函数？

Question

看来我在这里运气不好...很抱歉问你们。 :(

我正在尝试执行以下操作：

import multiprocessing
import time

class TestClass(multiprocessing.Process):
    def __init__(self):
        super(TestClass, self).__init__()
        print("Initializing the test class...")
        self.VARIABLE = 0

    def run(self):
        while self.VARIABLE < 10:
            print("Sleeping... Variable now: " + str(self.VARIABLE))
            time.sleep(1)

    def setVar(self, VALUE):
        print("Setting new value from " + str(self.VARIABLE) + " to " + str(VALUE) + " ...")
        self.VARIABLE = VALUE


if __name__ == "__main__":
    TESTPROCESS = TestClass()
    TESTPROCESS.start()
    time.sleep(5)
    TESTPROCESS.setVar(5)
    time.sleep(5)
    TESTPROCESS.setVar(10)

然而，在结果中，它不会更新运行() 中的 self.VARIABLE，而只会更新 setVar() 中的 self.VARIABLE。

c:\Python35\python.exe Test.py
Initializing the test class...
Sleeping... Variable now: 0
Sleeping... Variable now: 0
Sleeping... Variable now: 0
Sleeping... Variable now: 0
Sleeping... Variable now: 0
Setting new value from 0 to 5 ...
Sleeping... Variable now: 0
Sleeping... Variable now: 0
Sleeping... Variable now: 0
Sleeping... Variable now: 0
Sleeping... Variable now: 0
Setting new value from 5 to 10 ...
Sleeping... Variable now: 0
Sleeping... Variable now: 0
[...]

我想，"self" 会表明，这是 "global" 个参数，用于此 class/object?

即使我修改运行() 函数使其具有 "while true: --> break" 循环，同样的问题仍然出现。我的思维错误在哪里？

提前致谢...

Answer 1

TESTPROCESS.start() causes the run() method to be executed in a separate process; that's kind of the entire point. As a result, you do not have one TestClass instance; you have two, and they exist in separate processes. One of these instances is updated by your calls to setVar, and the other (due to being a different object) is not. If you want to be able to communicate between processes, look into pipes and queues.

Python 多处理："self."变量未更新in/by其他函数？

Python multiprocessing: "self."variable not updated in/by other functions?

python

local-variables

python-multiprocessing