在python中并行调用多个对象的方法

我有两节课。一个叫 algorithm 另一个打电话来 Chain . 在 算法

换言之 算法 类实例化n个链,我想运行 _sample 方法,它属于 类中的每个平行链 班级。

我在这里看到过类似的问题: Apply a method to a list of objects in parallel using multi-processing ,但如函数所示 _sample_chains_parallel_worker

问题1 :为什么在这种情况下不起作用?

sample_chains_parallel 甚至不并行运行。

问题2 :为什么?

问题3

import time
import multiprocessing

class Chain():

    def __init__(self):
        self.thetas = []

    def _sample(self):
        for i in range(3):
            time.sleep(1)
            self.thetas.append(i)

    def clear_thetas(self):
        self.thetas = []

class algorithm():

    def __init__(self, n=3):
        self.n = n
        self.chains = []

    def _init_chains(self):
        for _ in range(self.n):
            self.chains.append(Chain())

    def _sample_chains(self):
        for chain in self.chains:
            chain.clear_thetas()
            chain._sample()

    def _sample_chains_parallel(self):
        pool = multiprocessing.Pool(processes=self.n)
        for chain in self.chains:
            chain.clear_thetas()
            pool.apply_async(chain._sample())
        pool.close()
        pool.join()

    def _sample_chains_parallel_worker(self):

        def worker(obj):
            obj._sample()

        pool = multiprocessing.Pool(processes=self.n)
        pool.map(worker, self.chains)

        pool.close()
        pool.join()


if __name__=="__main__":
    import time

    alg = algorithm()
    alg._init_chains()

    start = time.time()
    alg._sample_chains()
    end = time.time()
    print "sequential", end - start

    start = time.time()
    alg._sample_chains_parallel()
    end = time.time()
    print "parallel", end - start

    start = time.time()
    alg._sample_chains_parallel_worker()
    end = time.time()
    print "parallel, map and worker", end - start