Python 多进程 一分钟下载二百张图片 是什么样子的体验

需要爬取国内某个网站，但是这个网站封ip，没办法，只能用代理了，然后构建自己的代理池，代理池维护了20条进程，

所用的网络是20M带宽，实际的网速能达到2.5M，考虑到其他原因，网速未必能达到那么多。爬虫对网速的要求挺高的。

首先把 URL 图片的链接  抓取下来 保存到数据库中去，然后使用多进程进行图片的抓取。

经过测试   开40个进程，一分钟能采集200张图片，但是开60个进程，图片下降到了一分钟120张。

注意： 抓取图片的时候，或者抓取视频的时候，一定要加上请求头，实现图片的压缩传输。

下面直接粘贴出来代码：

# coding:utf-8
from common.contest import *

def save_img(source_url, dir_path, file_name,maxQuests= 11):
    maxQuests =maxQuests

    headers = {

                "Host":"img5.artron.net",
                "Connection":"keep-alive",
                "User-Agent":"Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.91 Safari/537.36",
                "Accept":"image/webp,image/apng,image/*,*/*;q=0.8",
                "Referer":"http://auction.artron.net/paimai-art5113610001/",
                "Accept-Encoding":"gzip, deflate",
                "Accept-Language":"zh-CN,zh;q=0.8",

                }
    proxies = r.get(str(random.randint(1,10)))
    proxies = {"http": "http://" + str(proxies)}
    print "使用的代理是：",proxies
    try:
        response = requests.get(url=source_url, headers=headers,verify=False,proxies=proxies,timeout=15)
        if response.status_code == 200:
            if not os.path.exists(dir_path):
                os.makedirs(dir_path)
            total_path = dir_path + '/' + file_name

            with open(total_path, 'wb') as f:
                for chunk in response.iter_content(1024):
                    f.write(chunk)
            print "图片保存到本地"
            return ""
        else:
            print "图片没有保存到本地"
            return ""
    except Exception as e:
        print e
        if maxQuests > 0 and response.status_code != 200:
            save_img(source_url, dir_path, file_name, maxQuests-1)

def getUpdataImage(item):

    item_imgurl = item['item_imgurl']
    url = item_imgurl
    item_href = item_imgurl
    print "正在采集的 url 是",url

    filenamelist = url.split('/')

    filename1 = filenamelist[len(filenamelist) - 4]
    filename2 = filenamelist[len(filenamelist) - 3]
    filename3 = filenamelist[len(filenamelist) - 2]
    filename4 = filenamelist[len(filenamelist) - 1]

    filename = filename1 + "_" + filename2 + "_" + filename3 + "_" + filename4

    filenamestr = filename.replace('.jpg', '')
    filenamestr = filenamestr.replace('.JPG', '')
    filenamestr = filenamestr.replace('.JPEG', '')
    filenamestr = filenamestr.replace('.jpeg', '')
    filenamestr = filenamestr.replace('.png', '')
    filenamestr = filenamestr.replace('.bmp', '')
    filenamestr = filenamestr.replace('.tif', '')
    filenamestr = filenamestr.replace('.gif', '')

    localpath = 'G:/helloworld/' + filenamestr

    save_localpath = localpath + "/" + filename
    print "图片保存路径是:",save_localpath

    try:
        result = save_img(url, localpath, filename,item_href)

        if result == "":
            print "图片采集成功"
        else:
            print "图片采集失败"

    except IOError:
        pass

if __name__ == "__main__":

    time1 = time.time()
    sql = """SELECT item_id, item_imgurl FROM 2017_xia_erci_pic  """
    resultList = select_data(sql)
    print len(resultList)
    pool = multiprocessing.Pool(60)
    for item in resultList:
        pool.apply_async(getUpdataImage, (item,))
    pool.close()
    pool.join()