python并发模块之concurrent.futures(二)

上次我们简单的了解下，模块的一些基本方法和用法，这里我们进一步对concurrent.futures做一个了解和拓展.
上次的内容点这。
python并发模块之concurrent.futures(二)
以下载图片为例子，下面的程序是顺序下载http://www.58pic.com/newpic/28660111.html网站的24个表情 。

from requests_html import HTMLSession
import os
import time

BASE_PATH="downloads"
class Get_Image():

    def __init__(self):

        self.timeout=20

        self.session=HTMLSession()

    def getiamge(self,url):

        req=self.session.get(url,timeout=self.timeout)

        if req.status_code==200:

            imgurllist=req.html.xpath("//ul[@class='emoticon-model']/li/img/@data-big")

            for index,url in enumerate(imgurllist):

                print(f"开始下载第{index+1}张图片")

                self.save_image(url,index+1)

        else:

            print("下载失败")

    def save_image(self,imgurl,index):

        print(f"当前下载链接：{imgurl}")

        buff=self.session.get(imgurl,timeout=self.timeout).content

        file_path=os.path.join(os.path.dirname(os.path.abspath(__file__)),BASE_PATH)

        if not os.path.exists(file_path):

            os.makedirs(file_path)

        with open(os.path.join(file_path,f"{index}.png"),"wb") as fs:

            fs.write(buff)
if __name__ == '__main__':

    start_url="http://www.58pic.com/newpic/28660111.html"

    start=time.time()

    Get_Image().getiamge(start_url)

    end=time.time()

    print(f"顺序下载24张图片用时:{end-start}")
#运行了两次结果分别为
#顺序下载24张图片用时:14.926000356674194
#顺序下载24张图片用时:14.07800030708313

使用concurrent.futures修改成并发之后

from requests_html import HTMLSession
import os
import time
from concurrent.futures import ThreadPoolExecutor

BASE_PATH="downloads"

MAX_WORKERS = 10 #最多使用10个线程
class Get_Image():

    def __init__(self):

        self.timeout=20

        self.session=HTMLSession()

    def getiamge(self,url):

        req=self.session.get(url,timeout=self.timeout)

        if req.status_code==200:

            imgurllist=req.html.xpath("//ul[@class='emoticon-model']/li/img/@data-big")

            works=min(len(imgurllist),MAX_WORKERS)

            with ThreadPoolExecutor(works) as excutor:

                res=excutor.map(self.save_image,imgurllist,range(1,25))

            return len(list(res))

        else:

            print("下载失败")

    def save_image(self,imgurl,index):

        print(f"当前下载链接：{imgurl}")

        buff=self.session.get(imgurl,timeout=self.timeout).content

        file_path=os.path.join(os.path.dirname(os.path.abspath(__file__)),BASE_PATH)

        if not os.path.exists(file_path):

            os.makedirs(file_path)

        with open(os.path.join(file_path,f"{index}.png"),"wb") as fs:

            fs.write(buff)
if __name__ == '__main__':

    start_url="http://www.58pic.com/newpic/28660111.html"

    start=time.time()

    Get_Image().getiamge(start_url)

    end=time.time()

    print(f"并发下载24张图片用时:{end-start}")
#运行了两次结果分别为
#并发下载24张图片用时:7.737000226974487
#并发下载24张图片用时:7.083999872207642

通过观察发现速度并发之后效率大大提高了。