nginx upstream module - delay in response for the 2nd request

I went through the EvanMillers Nginx tutorial, and wrote a simple nginx upstream module that does a GET from the backend redis server. The first request work perfectly fine, but for the second request the nginx the handler is only called after the first one is timed out (see attached image). Here is the code : https://gist.github.com/melwinjose/9c22c30eabe05b051a16