Comment 1 for bug 1903226

I can imagine this happening in 2 cases:
1. You've changed haproxy_balance_alg from source to smth else
2. You have dynamic IP's which can change during the session

`memcache_servers` value is a comma-separated list when it's actually the list, which is not the case when a balancer used in front of it. In this case keystone decides on which memcached server specific cache is stored. The problem here is that it doesn't have option to mark one of it DOWN when you have issue with controllers, which will result in timeouts.

When haproxy is used we rely on the source IP of the request to get service to the exact same memcached server as it was before. Otherwise you will get issues like described.

I'm using this config in several of production deployments on train for a year or so, and never experienced any issues with it