The article is about restarting HAProxy without any downtime. HAProxy restarts are needed when adding new service instances or adjusting configuration options. This is a different and much harder problem than gracefully restarting load balanced service instances.
As other posters have mentioned the solution in this link is actually suboptimal. I showed how the iptables solution leads to 1-3s latency for connections that establish during the restart but you can avoid it by getting a little more hardcore.
It should, and it allows you to do some changes over a socket, but allowing complete updates with the current haproxy architecture is a lot of work and isn't there yet.
