Just as a thought experiment, I was pondering the following: ZK stamps each change to its managed state with a zxid (http://hadoop.apache.org/zookeeper/docs/r3.2.1/zookeeperInternals.html). That ID consists of a 64 bit number in which the upper 32 bits are the epoch, which changes when the leader does, and the bottom 32 bits are a counter, which is incremented by the leader with every change. If 1000 changes are made to ZK state each second (which is 1/20th of the peak rate advertised), then the counter portion will roll over in 2^32 / (86400 * 1000) = 49 days.
Now, assuming that my math is correct, is this an actual concern? For example, if I'm using ZK to provide locking for a key value store that handles transactions at about that rate, am I setting myself up for failure? Thanks, Sandy