【12.1】事件循环

 1 #!/usr/bin/env python
 2 # -*- coding:utf-8 -*-
 3 
 4 # 事件循环+回调（驱动生成器）+epoll（IO多路复用）
 5 # asyncio是python用于解决异步io编程的一整套解决方案
 6 # tornado、gevent、twisted（scrapy，django channels）
 7 
 8 # 使用asyncio
 9 import asyncio
10 import time
11 
12 
13 async def get_html(url):
14     """
15     声明一个协程
16     """
17     print(‘start get url‘)
18     await asyncio.sleep(2)
19     print(‘end get url‘)
20 
21 
22 if __name__ == ‘__main__‘:
23     start_time = time.time()
24     # 创建loop
25     loop = asyncio.get_event_loop()
26     tasks = [get_html(‘http://www.imooc.com‘) for i in range(10)]
27     # 将任务提交
28     loop.run_until_complete(asyncio.wait(tasks))
29     print(time.time() - start_time)

 1 import asyncio
 2 import time
 3 from functools import partial
 4 
 5 
 6 async def get_html(url):
 7     """
 8     声明一个协程
 9     """
10     print(‘start get url‘)
11     await asyncio.sleep(2)
12     print(‘end get url‘)
13     return ‘zy‘
14 
15 
16 def callback(url, future):
17     print(url)
18     print(‘send email to zy‘)
19 
20 
21 if __name__ == ‘__main__‘:
22     start_time = time.time()
23     # 创建loop
24     loop = asyncio.get_event_loop()
25     get_future = asyncio.ensure_future(get_html(‘http://www.imooc.com‘))
26     # tasks = loop.create_task(get_html(‘http://www.imooc.com‘))
27     #
28     get_future.add_done_callback(partial(callback, ‘http://www.imooc.com‘))
29     # 将任务提交
30     loop.run_until_complete(get_future)
31     # 获取返回值
32     print(get_future.result())
33     print(time.time() - start_time)

 1 # wait和gather
 2 import asyncio
 3 import time
 4 
 5 
 6 async def get_html(url):
 7     """
 8     声明一个协程
 9     """
10     print(‘start get url‘)
11     await asyncio.sleep(2)
12     print(‘end get url‘)
13 
14 
15 if __name__ == ‘__main__‘:
16     start_time = time.time()
17     # 创建loop
18     loop = asyncio.get_event_loop()
19     # tasks = [get_html(‘http://www.imooc.com‘) for i in range(10)]
20     # # 一次提交多个任务
21     # loop.run_until_complete(asyncio.gather(*tasks))
22 
23     # wait和gather的区别
24     # gather更加high-level
25     group1 = [get_html(‘http://www.imooc.com‘) for i in range(10)]
26     group2 = [get_html(‘http://www.baidu.com‘) for i in range(10)]
27     group1 = asyncio.gather(*group1)
28     group2 = asyncio.gather(*group2)
29 
30     loop.run_until_complete(asyncio.gather(group1, group2))
31     print(time.time() - start_time)