Question

为什么我的dict不会更新？不是DictProxy的目的是处理这样的案件吗？

from multiprocessing import Pool, Manager 

def func(logtree):
    logtree['x'] = 'x'


def main():
    manager = Manager()
    logtrees = manager.dict()
    logtrees['a'] = {}
    logtrees['b'] = {}
    logtrees['c'] = {}

    pool = Pool(processes=2)
    for key in logtrees.keys():
        pool.apply_async(func, args=(logtrees[key],))

    pool.close()
    pool.join()
    print(logtrees)


if __name__ == '__main__':
    main()

实际输出：{'a': {}, 'b': {}, 'c': {}}

所需的输出：{'a': {'x': 'x'}, 'b': {'x': 'x'}, 'c': {'x': 'x'}}

Answer 1

我认为答案不正确。您用普通词典覆盖了经理。

logtrees = {key: dict(logtrees[key]) for key in logtrees.keys()}

您可以通过添加以下几行来观察这一点

from multiprocessing import Pool, Manager


def func(logtree):
    logtree['x'] = 'x'


def main():
    manager = Manager()
    logtrees = manager.dict()
    logtrees['a'] = manager.dict()
    logtrees['b'] = manager.dict()
    logtrees['c'] = manager.dict()

    pool = Pool(2)
    for key in logtrees.keys():
        pool.apply_async(func, args=(logtrees[key],))

    pool.close()
    pool.join()
    print(logtrees.__class__)  # <-------------------------------------- here
    logtrees = {key: dict(logtrees[key]) for key in logtrees.keys()}
    print(logtrees)
    print(logtrees.__class__)  # <-------------------------------------- here


if __name__ == '__main__':
    main()

输出：

<class 'multiprocessing.managers.DictProxy'>
{'a': {'x': 'x'}, 'b': {'x': 'x'}, 'c': {'x': 'x'}}
<class 'dict'>

我希望知识有所帮助

Answer 2

问题解决了！

from multiprocessing import Pool, Manager


def func(logtree):
    logtree['x'] = 'x'


def main():
    manager = Manager()
    logtrees = manager.dict()
    logtrees['a'] = manager.dict()
    logtrees['b'] = manager.dict()
    logtrees['c'] = manager.dict()

    pool = Pool(2)
    for key in logtrees.keys():
        pool.apply_async(func, args=(logtrees[key],))

    pool.close()
    pool.join()

    logtrees = {key: dict(logtrees[key]) for key in logtrees.keys()}
    print(logtrees)


if __name__ == '__main__':
    main()

从多个进程更新DictProxy不起作用

2 个答案: