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。