python - 并行独立进程

Question

我想在循环中启动多个进程，但由于它们需要很长时间才能完成，我认为并行运行它们可能会更好。所有这些过程都是独立的，即它们不依赖于彼此的结果。 这是一个小例子，说明了我正在处理的循环类型:

inDir = '/path/to/your/dir/'
inTxtList = ['a.txt','b.txt','c.txt','d.txt','e.txt']
for i in inTxtList:
    myfile = open(i,'w')
    myfile.write("This is a text file written in python\n")
    myfile.close()

我尝试了 multiprocessing 包并得出以下代码:

import multiprocessing

def worker(num):
    """thread worker function"""
    myfile = open(num,'w')
    myfile.write("This is my first text file written in python\n")
    myfile.close()
    return

if __name__ == '__main__':
    jobs = []
    for i in inTxtList:
        p = multiprocessing.Process(target=worker, args=(inDir+i,))
        jobs.append(p)
        p.start()
        p.join()

它确实有效，但我不知道如何设置 worker 数量。你能帮我吗？

Answer 1

使用multiprocessing.Pool.map 。您可以在创建 Pool 对象时通过指定 processes 参数来指定工作线程数量:

import os
import multiprocessing

def worker(num):
    with open(num, 'w') as f:
        f.write("This is my first text file written in python\n")

if __name__ == '__main__':
    number_of_workers = 4
    pool = multiprocessing.Pool(processes=number_of_workers)
    pool.map(worker, [os.path.join(inDir, i) for i in inTxtList])
    pool.close()
    pool.join()

顺便说一句，使用 os.path.join而不是手动连接路径组件。