在进程之间共享布尔值

Question

I\xe2\x80\x99m 希望在 Python 中的两个进程之间共享 bool 值。我有一个队列，我想通过让它在第一次运行 while 循环时填满来初始化。此后，布尔值设置为 true，其他进程现在可以开始从队列中读取。

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注意：我\xe2\x80\x99已经尝试使用值，但布尔不会\xe2\x80\x99t更新。我是否需要将 bool 作为参数传递给进程才能使其工作？

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另外，这是我的代码：

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#Main thread\nbool_val = Value(\xe2\x80\x9ci\xe2\x80\x9d, 0)\n\n#queue gets written to...\n\nbool_val = Value(\xe2\x80\x9ci\xe2\x80\x9d, 1)\n\n

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#other thread\nIf bool(bool_val) is True:\n    #read from queue\n

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Answer 1

如果您依赖于使用multiprocessing.Value - 该对象本身可以通过属性访问value。

这是一个原始的例子：

from multiprocessing import Process, Value, Queue, cpu_count, current_process


def handle(v):
    val = v.value
    if bool(val) is True:
        print('process {} is using value {}'.format(current_process().name, val))
    else:
        v.value = 1
        print('process {} changed value {} to {}'
              .format(current_process().name, val, v.value))


if __name__ == '__main__':
    v = Value('i', 0)

    processes = [Process(target=handle, args=(v,)) for _ in range(cpu_count())]
    for p in processes:
        p.start()

    for p in processes:
        p.join()

    print(v, v.value)

输出：

process Process-1 changed value 0 to 1
process Process-2 is using value 1
process Process-3 is using value 1
process Process-4 is using value 1
process Process-5 is using value 1
process Process-6 is using value 1
process Process-7 is using value 1
process Process-8 is using value 1
process Process-9 is using value 1
process Process-10 is using value 1
process Process-11 is using value 1
process Process-12 is using value 1
<Synchronized wrapper for c_int(1)> 1