python - 如何使用python的多处理模块

Question

我使用的是 Intel 的 Pentium(R)Dual-core E5700 @3.00GHz 和 2GB 内存。我正在尝试学习 Python 的 multiprocessing 模块。我写了一个简单的程序来执行加法，但它不起作用；我只是越来越多的核心 2。我的电脑或我的代码有问题吗？

import multiprocessing
print "number of core ",multiprocessing.cpu_count()



def calc(a,b):
    c= a+b
    return c

if __name__ =='__main__':

    p1 = multiprocessing.Process(target=calc,args=(3,5) )
    p1.start()
    p2 = multiprocessing.Process(target=calc,args=(2,2) )
    p2.start()



p1.join()
p2.join()

Answer 1

我建议你使用Queue .看这个例子:

from multiprocessing import Queue, Process

def calc(a, b, queue):
    queue.put(a + b)

if __name__ == '__main__':
    queue = Queue()
    p1 = Process(target = calc, args = (4, 4, queue,))
    p2 = Process(target = calc, args = (4, 4, queue,))
    p1.start()
    p2.start()
    result_1 = queue.get()
    result_2 = queue.get()
    print(result_1, result_2)
    p1.join()
    p2.join()
    input()

>>> 8 8

动态相同的代码:

from multiprocessing import Queue, Process, cpu_count

def calc(a, b, queue):
    queue.put(a + b)

if __name__ == '__main__':
    queue = Queue()
    processes = []
    for i in range(cpu_count()):
        processes.append(Process(target = calc, args = (4, 4, queue,)))
        processes[-1].start()
    results = []
    for i in range(cpu_count()):
        results.append(queue.get())
    print(results)
    for process in processes:
        process.join()

>>> [8, 8] # if you have two cores