使用 tornado.gen.Task 并没有获得异步的效果

Question

1. 原文连接: http://python.jobbole.com/84944/?utm_source=tuicool&utm_medium=referral#article-comment

2. 代码

   class AsyncTaskHandler(tornado.web.RequestHandler):

      @tornado.web.asynchronous
      @tornado.gen.coroutine
      def get(self, *args, **kwargs):
          response = yield tornado.gen.Task(self.ping, ' www.cnode.com')
          print 'response', response
          self.finish('hello')
   
      @tornado.gen.coroutine
      def ping(self, url):
          os.system("ping -c 2 {}".format(url))
          return 'after
   

3. 输出

   Server Software: TornadoServer/4.3
   Server Hostname: 127.0.0.1
   Server Port: 5000

   Document Path: /async/task
   Document Length: 5 bytes

   Concurrency Level: 5
   Time taken for tests: 0.049 seconds
   Complete requests: 5
   Failed requests: 0
   Total transferred: 985 bytes
   HTML transferred: 25 bytes
   Requests per second: 101.39 [#/sec] (mean)
   Time per request: 49.314 [ms] (mean)
   Time per request: 9.863 [ms] (mean, across all concurrent requests)
   Transfer rate: 19.51 [Kbytes/sec] received

4. 这个输出不对, 同样的代码, 我测试如下

   Concurrency Level: 5
   Time taken for tests: 6.599 seconds
   Complete requests: 5
   Failed requests: 0
   Total transferred: 985 bytes
   HTML transferred: 25 bytes
   Requests per second: 0.76 [#/sec] (mean)
   Time per request: 6599.359 [ms] (mean)
   Time per request: 1319.872 [ms] (mean, across all concurrent requests)
   Transfer rate: 0.15 [Kbytes/sec] received

5. 哪儿出了问题? 不知道是怎么测试出这个结果的? 想不明白.

Answer 1

os.system 是 block 的

Tornado 的 block 是基于网络的异步 IO

要想异步，用 http://www.tornadoweb.org/en/stable/process.html#tornado.process.Subprocess

Answer 2

为什么我使用时老师报错，用的是tornado==6.0.1
'tornado.gen' has no attribute 'Task'