In addition to upgrading to metrics3,
CASSANDRA-5657 switched to using a custom histogram implementation. After upgrading to Cassandra 2.2 histograms/timer metrics are not suspiciously flat. To be useful for graphing and alerting metrics need to be biased towards recent events.
I have attached images that I think illustrate this.
- The first two are a comparison between latency observed by a C* 2.2 (us) cluster shoring very flat lines and a client (using metrics 2.2.0, ms) showing server performance problems. We can't rule out with total certainty that something else isn't the cause (that's why we measure from both the client & server) but they very rarely disagree.
- The 3rd image compares jconsole viewing of metrics on a 2.2 and 2.1 cluster over several minutes. Not a single digit changed on the 2.2 cluster.