Requests being blocked client-side

[Maxim Dounin]

Hello!

On Fri, Apr 11, 2014 at 12:45:17PM -0400, justink101 wrote:

> I am seeing super strange behavior and I am absolutely stumped. If I open up
> two tabs in Google Chrome (34), and in the first refresh our application
> (foo.ourapp.com), which makes an ajax requests (via jQuery) that takes 20 or
> so seconds to complete. Then in the other new tab hit refresh on
> (foo.ourapp.com), the second tab blocks waiting until the ajax request on
> the first tab finishes. Inspecting Chrome developer tools shows:
> 
> http://cl.ly/image/1s3V353o1v2c
> 
> However, if I open up Firefox and load up (foo.ourapp.com) while the long
> running ajax request is firing in Chrome, it loads fine. Thus, I have
> determined that the client (Chrome) is blocking requests client-side.
> However, according to  http://www.browserscope.org/?category=network it says
> Chrome supports 6 connections per hostname, which should be fine, as I am
> only making two requests.
> 
> Any ideas on this? Pretty standard nginx config, with the following notable
> exceptions:
> 
>      listen 443 deferred ssl spdy;
> 
>      add_header Strict-Transport-Security max-age=31556926;
>      add_header X-XSS-Protection "1; mode=block";
>      add_header Access-Control-Allow-Origin $scheme://$account.myapp.com;
>      add_header X-Frame-Options DENY;
>      add_header X-Content-Type-Options nosniff;
> 
> Running nginx/1.5.12 with SPDY 3.1.

The "6 connections per hostname" is for normal http, not spdy - as 
spdy specification requires no more than 1 connection per server 
(as spdy allows to multiplex multiple requests within a single 
connection).  An obvious thing to check is if the problem goes 
away if you switch off spdy.

-- 
Maxim Dounin
http://nginx.org/