Change example.com.conf to set keep_conn just if your pools is static

[guiajlopes]

https://groups.drupal.org/node/229898#comment-1091368

[perusio]

Well not necessarily, because the connection is not directly to a child but to the fpm process as a all that then marshalls the requests to the children. The idea is to have a pool of keepalive connections so that when a PHP request comes the PHP FCGI module from nginx can proxy the request to php-fpm without having to establish a new TCP connection (thereby doing the 3 step handshake and so on).