Increasing timeouts causes browser to endlessly wait for a response

[Cocoa Guy]

Hi,

I'm running nginx 0.7.24 along with Mongrel. On an admin, non public
facing site, I have tasks that involve lots of computation and can
take up to 15-30 minutes to run.

I've configured nginx to wait a long while for a response from
Mongrel, but what happens is that Mongrel will complete the task, but
nothing is returned to the browser. It just sits there as if the
operation is still running.

Below is my configuration. This is what I'm using to increase the timeout:
            proxy_connect_timeout      3600;
            proxy_send_timeout         3600;
            proxy_read_timeout         3600;
            keepalive_timeout          3600;
            proxy_next_upstream off;

I've been trying to get this to work for over a day, so any hints are
greatly appreciated.
Cheers!

------------------
http {
    include       mime.types;
    default_type  application/octet-stream;

    log_format  main  '$remote_addr - $remote_user [$time_local] $request '
                      '\"$status\" $body_bytes_sent \"$http_referer\" '
                      '\"$http_user_agent\" \"$http_x_forwarded_for\"';

    access_log  logs/access.log  main;

    sendfile        on;

    gzip  on;
    gzip_http_version 1.0;
    gzip_comp_level 2;
    gzip_proxied any;
    gzip_types      text/plain text/html text/css
application/x-javascript text/xml application/xml application/xml+rss
text/javascript;

    upstream mongrel {
      server 127.0.0.1:8000;
      server 127.0.0.1:8001;
      server 127.0.0.1:8002;
    }

    server {
        listen       3000;
        server_name  blah.com;
        root   /blah/cache;

        if (-f $document_root/system/maintenance.html) {
          rewrite  ^(.*)$  /system/maintenance.html last;
          break;
        }

        location / {
            proxy_set_header  CLIENT_IP  $remote_addr;
            proxy_set_header  Host $http_host;

            proxy_connect_timeout      3600;
            proxy_send_timeout         3600;
            proxy_read_timeout         3600;
            keepalive_timeout          3600;
            proxy_next_upstream off;

            if (-f $request_filename) {
              break;
            }

            if (-f $request_filename/index.html) {
              rewrite (.*) $1/index.html break;
            }

            if (-f $request_filename.html) {
              rewrite (.*) $1.html break;
            }

            if (!-f $request_filename) {
              proxy_pass        http://mongrel;
              break;
            }
        }

        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }
    }
}