爬虫：单线程+多任务异步协程

from flask import Flask
import time

app = Flask(__name__)

@app.route(‘/index1‘)
def index_bobo():
    time.sleep(2)
    return ‘Hello index1‘

@app.route(‘/index2‘)
def index_jay():
    time.sleep(2)
    return ‘Hello index2‘

@app.route(‘/index3‘)
def index_tom():
    time.sleep(2)
    return ‘Hello index3‘

if __name__ == ‘__main__‘:
    app.run(threaded=True)

import time
import asyncio
s = time.time()
urls = [
    ‘http://127.0.0.1:5000/index1‘,
    ‘http://127.0.0.1:5000/index2‘,
    ‘http://127.0.0.1:5000/index3‘,
]

#在特殊函数内部的实现中不可以出现不支持异步的模块代码
async def get_request(url):
    #aiohttp:支持异步网络请求的模块
   async with aiohttp.ClientSession() as s:     #创建一个aiohttp的ClientSession对象
       async with await s.get(url=url) as response:       #发起aio请求
           page_text = await response.text()
           print(page_text)
   return page_text
tasks = []
for url in urls:
    c = get_request(url)            #协程对象
    task = asyncio.ensure_future(c)     #将协程对象进一步封装，即是任务对象 ，任务对象==高级的协程对象==特殊的函数
    tasks.append(task)

loop = asyncio.get_event_loop() #创建事件循环对象
#注意：挂起操作需要手动处理
loop.run_until_complete(asyncio.wait(tasks))  #事件循环对象支持异步，将任务对象添加到事件循环中，启动事件循环，
                                                # 对任务对象进行异步执行

print(time.time()-s)

from multiprocessing.dummy import Pool
import requests
import time
start = time.time()
urls = [
    ‘http://localhost:5000/index1‘,
    ‘http://localhost:5000/index‘,

]
def get_request(url):
    page_text = requests.get(url).text
    print(page_text)

pool = Pool(5)
pool.map(get_request, urls)

print(‘总耗时：‘, time.time() - start)