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GitHub Repository: jackfrued/Python-100-Days
 Path: blob/master/Day16-20/code/example24.py
Views: 729
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"""

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aiohttp - 异步HTTP网络访问

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异步I/O（异步编程）- 只使用一个线程（单线程）来处理用户请求

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用户请求一旦被接纳，剩下的都是I/O操作，通过多路I/O复用也可以达到并发的效果

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这种做法与多线程相比可以让CPU利用率更高，因为没有线程切换的开销

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Redis/Node.js - 单线程 + 异步I/O

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Celery - 将要执行的耗时间的任务异步化处理

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异步I/O事件循环 - uvloop

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"""

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import asyncio

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import re

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import aiohttp

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async def fetch(session, url):

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    async with session.get(url, ssl=False) as resp:

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        return await resp.text()

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async def main():

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    pattern = re.compile(r'\<title\>(?P<title>.*)\<\/title\>')

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    urls = ('https://www.python.org/',

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            'https://git-scm.com/',

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            'https://www.jd.com/',

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            'https://www.taobao.com/',

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            'https://www.douban.com/')

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    async with aiohttp.ClientSession() as session:

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        for url in urls:

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            html = await fetch(session, url)

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            print(pattern.search(html).group('title'))

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if __name__ == '__main__':

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    loop = asyncio.get_event_loop()

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    loop.run_until_complete(main())

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    loop.close()

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