Capturing JVM- and application-level metrics. So you know what's going on.
Capturing meaningful metrics in your Java application
Metrics reporter, which reports to elasticsearch
An application metrics facade for the most popular monitoring tools. Think SLF4J, but for metrics.
Metrics + Hyperic Sigar for OS-level monitoring
Ruby metric reports for Jenkins. Rcov, Rails stats, Rails notes and Flog.
Detect janky frames with Android Nougat FrameMetrics