Round robin a list from Phoenix app

Hi,
I’ve a list of IP addresses (5) that I can connect to from my phoenix web application, what will be the best way to implement a round robin algorithm on the list of IPs, I thought about using a GenServer and maintaining it’s state as the IPs, in that case I’ve a serialised access to the list and can handoff the IPs in a serialised manner. My fear is that the GenServer could a bottleneck to the application when I’ve a lot of requests.