关于并发，异步，非阻塞(python)疑惑的一些资料解答

从iterable/iterator到generator到coroutine
理解python的迭代器: http://python.jobbole.com/81916/
理解python的生成器: http://python.jobbole.com/81911/
python中协程:http://python.jobbole.com/87156/

从yield/send到yield from/asycio到asyc/awati
Python协程从yield/send到async/await: http://python.jobbole.com/86069/
深入理解 Python 异步编程(上):http://python.jobbole.com/88291/

服务器是如何承受大量的用户请求的:https://www.zhihu.com/question/27629526
flask是如何处理多个访问请求的：https://segmentfault.com/q/1010000004532745
tornado 异步笔记:https://www.jianshu.com/p/31fae7dd05ba

tornado和flask异步的例子,请求非阻塞

 #-*-coding:utf8-*-

 import tornado.httpserver
 import tornado.ioloop
 import tornado.options
 import tornado.web

 import time
 import os
 import urllib.request
 from tornado.options import define,options
 define("port",default=8000,help="run on the given port",type=int)

 class Async1Handler(tornado.web.RequestHandler):
     @tornado.web.asynchronous
     @tornado.gen.coroutine
     def get(self,*args,**kwargs):
         print("begin!")
         response = yield tornado.gen.Task(self.open)
         print(response)
         self.finish("it works")

     @tornado.gen.coroutine
     def open(self):

         return (urllib.request.urlopen('http://127.0.0.1:5000/asyn/'))
         #os.system("ping -c 5 127.0.0.1")

 if __name__ == "__main__":
     tornado.options.parse_command_line()
     print("****listening 127.0.0.1:8000****")
     app = tornado.web.Application(
                 handlers=[(r'/async',Async1Handler)],
                 debug="True")
     http_server = tornado.httpserver.HTTPServer(app)
     http_server.listen(options.port)
     tornado.ioloop.IOLoop.instance().start()

 # coding=utf-8
 # Python Version: 3.5.1

 # Flask
 from flask import Flask, request, g
 import urllib.request

 import os
 from gevent import monkey
 from gevent.pywsgi import WSGIServer
 monkey.patch_all()

 import time

 app = Flask(__name__)
 app.config.update(DEBUG=True)

 @app.route('/asyn/', methods=['GET'])
 def test_asyn_one():
     print("asyn has a request!")
     #print(urllib.request.urlopen('http://127.0.0.1:8000/async1'))
     os.system("ping -c 5 127.0.0.1")
     return 'hello asyn'

 if __name__ == "__main__":
     # app.run()
     http_server = WSGIServer(('', 5000), app)
     http_server.serve_forever()