如何在python中使用多处理为变量赋值新值

Posted 2021-04-13

def foo(var, new_value):
    var = new_value

x = 1
multiprocessing.Process(target=foo, args=(x,2))
p.start()
p.join()
print(x)

我希望print(x)的输出是2，但事实上我得到1.我怎么能为现有变量赋值？

答案

你需要使用multiprocessing shared values;

import multiprocessing
import ctypes

def foo(var, new_value):
    var.value = new_value

x = multiprocessing.Value(ctypes.c_int, 1)
print(x.value)
p = multiprocessing.Process(target=foo, args=(x,2))
p.start()
p.join()
print(x.value)