We have a 3-node ZK cluster running 3.3.4 that are experiencing high
latency. From "stat", we saw avg latency to be 300-400ms consistently.
Outstanding requests jumps to ~600 from time to time. However, the server's
I/O and CPU are both low. If I start a new ZK client and do a few writes,
the observed response time in the client is also low (1ms).
What's the best way to figure out why the reported latency in ZK server is
high? Also, are min/avg/max latency computed on a rolling time window?