12.15日进步单进程和双进程_双进程转单-优快云博客

本文介绍了一种使用Python多进程技术进行网页数据抓取的方法，通过对比单进程与多进程的执行效率，展示了多进程在处理大规模数据时的优势。文章详细讲解了如何利用multiprocessing模块并行执行网络请求，加速数据抓取过程。

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代码

# coding=utf-8
import multiprocessing
import os
from pyquery import PyQuery as pq
import requests
import csv
import time

def action(key):
    head = {
    'Upgrade-Insecure-Requests':'1',
    'User-Agent':'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36'
    }
    for i in range(1,50):
        page = []
        url = 'https://www.yuanjisong.com/consultant/allcity/' + key + '/page' + str(i)
        response = requests.get(url,headers=head)
        doc = pq(response.text)
        boxs = doc('.weui_panel.weui_panel_access.weui_panel_access_adapt.db_adapt.margin-top-2').items()  
        for box in boxs:
            box_text = box.text()
            page.append(box_text.split('\n'))
        path = 'I:/'+ key + '.csv'
        with open(path,'a',encoding='utf-8-sig') as f:
            writer = csv.writer(f)
            writer.writerows(page)
        print('保存' + key + '第' + str(i) + '页！')

单进程测试代码：

if __name__ == '__main__':
    a = time.time()
    action('python')
    action('java')
    print('it\'over!')
    print('单进程花费时间',time.time() - a)

花费时间：
111

双进程测试代码

if __name__ == '__main__':
    a = time.time()
    mp1 = multiprocessing.Process(target=action,args=('python',))
    mp1.start()
    mp2 = multiprocessing.Process(target=action,args=('java',))
    mp2.start()
    mp2.join()
    print('it\'over!')
    print('多进程花费时间',time.time() - a)

花费时间：
在这里插入图片描述

多进程池（数据量是刚才上面两个的10倍）

if __name__ == '__main__':
    a = time.time()
    keys =['java','php','python','node','net','ruby','cplus',\
        'quanzhan','ios','android','qianduan','houduan','ui','chanpin','yunying','ceshi','other']
    #数据成倍的增加
    pool = multiprocessing.Pool(processes=len(keys))
    pool.map(action,keys)
    pool.close()
    pool.join()
    print('it\'s over!')
    print('多进程花费时间',time.time() - a)

花费时间：
在这里插入图片描述