tornado 异步

def asynchronous(method):
    """Wrap request handler methods with this if they are asynchronous.

    This decorator is for callback-style asynchronous methods; for
    coroutines, use the ``@gen.coroutine`` decorator without
    ``@asynchronous``. (It is legal for legacy reasons to use the two
    decorators together provided ``@asynchronous`` is first, but
    ``@asynchronous`` will be ignored in this case)

    asynchronous注解是适用于回调函数写法
    用了gen.coroutine，无需再添加asynchronous注解


    This decorator should only be applied to the :ref:`HTTP verb
    methods <verbs>`; its behavior is undefined for any other method.
    This decorator does not *make* a method asynchronous; it tells
    the framework that the method *is* asynchronous.  For this decorator
    to be useful the method must (at least sometimes) do something
    asynchronous.
    该注解不是创建一个异步方法，而是告诉tornado这是一个异步方法，
    这个异步方法里面必须有异步方法

    If this decorator is given, the response is not finished when the
    method returns. It is up to the request handler to call
    `self.finish() <RequestHandler.finish>` to finish the HTTP
    request. Without this decorator, the request is automatically
    finished when the ``get()`` or ``post()`` method returns. Example:
    最后通过finish 方法结束http请求，否则客户端一直处于等待状态
   
    .. testcode::

       class MyRequestHandler(RequestHandler):
           @asynchronous
           def get(self):
              http = httpclient.AsyncHTTPClient()
              http.fetch("http://friendfeed.com/", self._on_download)

           def _on_download(self, response):
              self.write("Downloaded!")
              self.finish()


http://www.cnblogs.com/apexchu/p/4226784.html