My python tornado code doesn't work… why

Question

I have two Handler class to compare the @tornado.web.asynchronous decorator

class Test1Handler(tornado.web.RequestHandler):  
    def get(self):  
        for i in range(1, 100000):  
            print "kill time"  
        self.write("hello")  

class Test2Handler(tornado.web.RequestHandler):  
    @tornado.web.asynchronous
    def get(self):  
        http = tornado.httpclient.AsyncHTTPClient()  
        http.fetch("http://localhost:8005/test1", callback=self._test_callback)  
        self.write("Hello to the Tornado world! ")  

    def _test_callback(self, response): 
        print response.body
        self.write(response.body)  

The following is the configuration code

app = tornado.web.Application([
    (r'/test1', Test1Handler),
    (r'/test2', Test2Handler)], debug=True)
app.listen(8005)
tornado.ioloop.IOLoop.instance().start()

OK, when I run http://localhost:8005/test1 I can see the hello after several seconds...

However when I run http://localhost:8005/test2 , the page is just loading and loading... I should see Hello to the Tornado world! Hello Hello to the Tornado world! Hello But I can never see the last Hello word...

What's wrong with my code ?

Answer 1

You need to explicitly call finish method to finish http request when you're using tornado.web.asynchronous decorator.

def _test_callback(self, response): 
    self.write(response.body)  
    self.finish()  # <------

Answer 2

You seem to be missing a self.finish() in the handler decorated as asynchronous .

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() to finish the HTTP request.