Capturing JVM- and application-level metrics. So you know what's going on.
Metrics comes with five types of metrics:
* Gauges are instantaneous readings of values (e.g., a queue depth).
* Counters are 64-bit integers which can be incremented or decremented.
* Meters are increment-only counters which keep track of the rate of events. They provide mean rates, plus exponentially-weighted moving averages which use the same formula that the UNIX 1-, 5-, and 15-minute load averages use.
* Histograms capture distribution measurements about a metric: the count, maximum, minimum, mean, standard deviation, median, 75th percentile, 95th percentile, 98th percentile, 99th percentile, and 99.9th percentile of the recorded values. (They do so using a method called reservoir sampling which allows them to efficiently keep a small, statistically representative sample of all the measurements.)
* Timers record the duration as well as the rate of events. In addition to the rate information that meters provide, timers also provide the same metrics as histograms about the recorded durations. (The samples that timers keep in order to calculate percentiles and such are biased towards more recent data, since you probably care more about how your application is doing now as opposed to how it's done historically.)
Metrics also has support for health checks
Code:
https://github.com/codahale/metrics Presentation:
http://codahale.com/codeconf-2011-04-09-metrics-metrics-everywhere.pdf
