I’m using etcd, it does the same thing as zookeeper. Maybe i wasn’t clear enough, the problem is when a elected master loose the master because it didn’t update the lease for any reason (network, overhead, …) and another node is elected as master.
During a short, but existent, period of time, the old master still think it’s the master and can operate as it and the new elected master assumes and start operating, in this period of time, the cluster can have a wrong behaviour.
Don’t caught this problem yet in production. Looking at the code, it’s possible to happen. But as i’m not seeing a easy way to solve this, i’m gonna risk and resolve this problem only when it happens.