for循环上的Python多处理 [英] Python multi processing on for loop

问题描述

我有一个带有两个参数的函数

I have a function with two parameters

reqs =[1223,1456,1243,20455]
url = "pass a url"
def crawl(i,url):
   print("%s is %s" % (i, url))

我想通过多处理概念来触发上述功能.

I want to trigger above function by multi processing concept.

from multiprocessing import Pool

if __name__ == '__main__':
    p = Pool(5)   
    print(p.map([crawl(i,url) for i in reqs]))

以上代码对我不起作用.谁能帮我这个忙！

above code is not working for me. can anyone please help me on this!

-----添加新代码---------

----- ADDING NEW CODE ---------

from multiprocessing import Pool

reqs = [1223,1456,1243,20455]
url = "pass a url"

def crawl(combined_args):
   print("%s is %s" % (combined_args[0], combined_args[1]))

def main():
    p = Pool(5)   
    print(p.map(crawl, [(i,url) for i in reqs]))

if __name__ == '__main__':
    main()

当我尝试执行以上代码时，我遇到了错误

when I am trying to execute above code, I am getting below error

推荐答案

问题已解决.抓取功能应在单独的模块中，如下所示:

Issue resolved. crawl function should in separate module like below:

crawler.py

def crawl(combined_args):
   print("%s is %s" % (combined_args[0], combined_args[1]))

run.py

from multiprocessing import Pool
import crawler

def main():
    p = Pool(5)   
    print(p.map(crawler.crawl, [(i,url) for i in reqs]))

if __name__ == '__main__':
    main()

然后输出如下:

**output :**

1223 is pass a url
1456 is pass a url
1243 is pass a url
20455 is pass a url
[None, None, None, None]  # This is the output of the map function

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