Minor Description
HBASE-16388 introduced a new configuration setting "hbase.client.perserver.requests.threshold " to deal with slow region servers. I have back-ported the code for the new config setting to our environment, but I don't feel comfortable setting it in production without visibility into how the number of concurrent calls per server varies (especially the current high water mark or max in production when the cluster is healthy).
It is straightforward to pass the value for the concurrent calls per server to a new histogram in MetricsConnection. I will attach a patch that I am using to gain a better understanding of how setting "hbase.client.perserver.requests.threshold" will affect our production environment.