Capturing and exposing application metrics via JMX. For funsies.
- Java SE 6
- Scala 2.8 Beta1
First, specify Metrics as a dependency:
val codaRepo = "Coda Hale's Repository" at "http://repo.codahale.com/"
val metrics = "com.yammer" % "metrics_2.8.0.Beta1" % "1.0" withSources()
(Or whatever it takes for you to get Maven or Ivy happy.)
Second, instrument your classes:
import com.yammer.metrics.{Counter, Meter, Timer}
class ThingFinder {
private val resultsMeter = new Meter
private val dbTimer = new Timer
def findThings() = {
val results = dbTimer.time {
// perform an action which gets timed
Database.query("WHOO")
}
// calculate the rate of new things found
resultsMeter.mark(results.size)
// etc.
}
}
(You also might like LoadMeter, a meter class which provides 1-minute,
5-minute, and 15-minute moving weighted averages, much like the load values in
top. It's generally a more useful metric than Meter's averaged rate.)
Third, expose these metrics via JMX:
import java.util.concurrency.TimeUnit
import com.yammer.jmx.JmxManaged
class ThingFinder extends JmxManaged {
private val resultsMeter = new Meter
private val dbTimer = new Timer
enableJMX("our thing processor") { jmx =>
// exposes the total count of results, plus the results/sec rate
jmx.addMeter("results", resultsMeter, TimeUnit.SECONDS)
// exposes the count, max, min, mean, stddev, and 99.9th percentile of
// query timings in milliseconds
jmx.addTimer("database-query", dbTimer, TimeUnit.MILLISECONDS)
}
def findThings() = {
// etc.
}
}
Copyright (c) 2010 Coda Hale, Yammer.com Published under The MIT License, see LICENSE