python学习笔记 - asynchronous@tornado 学习记录一
Tornado是一款非阻塞web server,今天做了一个很简单的尝试
non-blocking I/O, 我简单的理解是“允许某一个操作可以继续进行,而不必等待某一资源的响应,预提供一个回调函数,用于处理、响应该资源的结果(当该资源返回相关内容的时候)”
对比异步I/O,我们最常见的就是同步I/O(线性编程),一次请求访问另一个资源,必须等待该资源的成功返回,方可进行下一步操作,如果该资源无响应(或异常),程序就终止(受限)于此。
更多异步I/O,可以参考:
http://en.wikipedia.org/wiki/Asynchronous_IO
这里我个人很浅显地描述下sync/async的大致对比:
下面就是我的测试代码:
async_sync_test_invoke3.py,一个普通的web app,将会被用于异步请求的调用
import loggingimport tornado.httpserverimport tornado.ioloopimport tornado.webclass MainHandler(tornado.web.RequestHandler): def get(self): ''' The below is only a testing which will be exected to kill time, and then we can find the asynchronous effect from the front page. ''' for i in range(1, 100000): print "kill time" self.write("hello")settings = { #"debug": True,}application = tornado.web.Application([ (r"/async-sync-test/", MainHandler),], **settings)if __name__ == "__main__": http_server = tornado.httpserver.HTTPServer(application) http_server.listen(8084) tornado.ioloop.IOLoop.instance().start()
import loggingimport tornado.httpserverimport tornado.ioloopimport tornado.webfrom tornado.httpclient import AsyncHTTPClientclass MainHandler(tornado.web.RequestHandler): @tornado.web.asynchronous def get(self): http = tornado.httpclient.AsyncHTTPClient() http.fetch("http://localhost:8084/async-sync-test/", callback=self._test_callback) self.write("Hello to the Tornado world! ") ''' Flushes the current output buffer to the network. ''' self.flush() ''' _test_callback is a callback function used for the processing of the response from the async request ''' def _test_callback(self, response): self.write(response.body) ''' refer the offical document, we are responsible for the invocation of the finish function in the async case. ''' self.finish()settings = { #"debug": True,}application = tornado.web.Application([ (r"/", MainHandler),], **settings)if __name__ == "__main__": http_server = tornado.httpserver.HTTPServer(application) http_server.listen(8083) tornado.ioloop.IOLoop.instance().start()