Keepalive not working with upstream tcp server

[Jayadev C]

I am trying to use nginx to proxy my requests to a custom tcp backend server that I have. I am following the same model as the default memcached module with in the nginx code base (1.5.10) , the relevant config file attached.  Tried with most of the keepalive options but I still see new connections getting created to upstream server. (rather I do see the connection getting closed by nginx in strace)


Do I need to specifically compile nginx with http upstream keepalive module, thought it was default enabled but the code doesn't seem to go through it looking in gdb.  Is there any other specific module  or setting I need to use for the upstream tcp persistent connection usecase.

Thanks in advance,
Jayadev


--- nginx.conf------

http {
    default_type  application/octet-stream;
    keepalive_timeout  100;
    proxy_http_version 1.1;

    upstream my_backend {
            server 127.0.0.1:1111;
            keepalive 100;
    }

    server {
         listen       4080;
         keepalive_timeout  100;
         keepalive_requests 100000;
         proxy_http_version 1.1;
         proxy_set_header Connection keepalive;

         location / {
                 root   html;
                 index  index.html index.htm;
                 my_pass my_backend;
         }
    }
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