在多处理中作为参数传递锁。为什么有效?

在下面的代码片段中,我通过打印锁对象的地址看到,每个进程都会获得锁对象的一个副本。

""" Processes and Locks """

import multiprocessing as mp
import logging


logging.basicConfig(level=logging.DEBUG,
                    format='(%(processName)-10s) (%(threadName)-9s) %(message)s',)


def increase_value(iterations, value, lock):
    """Increase a shared variable"""
    print(hex(id(lock)))
    for _ in range(iterations):
        lock.acquire()
        value.value = value.value + 1
        lock.release()


def decrease_value(iterations, value, lock):
    """Decrease a shared variable"""
    print(hex(id(lock)))
    for _ in range(iterations):
        lock.acquire()
        value.value -= 1
        lock.release()


if __name__ == "__main__":
    ITERATIONS = 100000
    SHARED_VALUE = mp.Value('i', 0)
    LOCK = mp.Lock()
    print(hex(id(LOCK)))
    t1 = mp.Process(target=increase_value, 
                    args=(ITERATIONS, SHARED_VALUE, LOCK))
    t2 = mp.Process(target=decrease_value, 
                    args=(ITERATIONS, SHARED_VALUE, LOCK))

    t1.start()
    t2.start()

    t1.join()
    t2.join()

    logging.debug("SHARED VALUE %d", SHARED_VALUE.value)

为什么会这样?锁如果它们引用相同的锁,则acquire应该有意义。我错过了什么?