How to create a non-blocking function?

Question

I am new to tornado.

It's exciting about the part of Coroutines.

So i try to convert a blocking function into a non-blocking at first.

@tornado.concurrent.return_future
def calculate(callback):
    start_time = time.time()
    res = urllib2.urlopen("https://www.google.com/")
    print time.time()-start_time
    callback(res)

class MainHandler(tornado.web.RequestHandler):

    @tornado.gen.coroutine
    def get(self):
        start_time = time.time()
        res = yield [calculate(), calculate()]
        print time.time()-start_time

But i got:

1.41436505318
1.38487792015
2.80179595947

It's I/O bound, so i guess the total time spent should be approximate to the longer one time spent(1.41436505318). But it seems to be blocking.

So i am wondering what's going wrong?How can i convert a blocking function into a non-blocking function?

Answer 1

return_future doesn't make a function non-blocking; it takes a non-blocking function that uses callbacks and makes it coroutine-friendly.

The only way to make a blocking function non-blocking without making deep changes to it is to run it in another thread or process, as with a ThreadPoolExecutor .