Reporting

Once you’ve started tracking some metrics there are several ways you can read their values.

More reporting methods will be added in the future. Pull requests are welcome.

Console

metrics-clojure supports reporting metrics through the console (on standard error):

(require '[metrics.reporters.console :as console])

(def CR (console/reporter reg {}))
(console/start CR 10)

This will tell metrics to print all metrics to the console every ten seconds.

Optional arguments to console/reporter are:

  • :stream
  • :locale
  • :clock
  • :rate-unit
  • :duration-unit
  • :filter

CSV Reporting

metrics-clojure supports reporting metrics into csv files (one file per metric):

(require '[metrics.reporters.csv :as csv])

(def CR (csv/reporter reg "/tmp/csv_reporter" {}))
(csv/start CR 1)

This will tell metrics to append the most recent value or each metric (every second), to a file named after the metric, in /tmp/csv_reporter. The directory name is required. The directory (and parents) will be created if they doesn’t exist, it will throw an exception if it is not writable, or if the given path is not a directory.

To use this reporter, you may need to sanitize your metric names to ensure that they are valid filenames for your system.

Optional arguments to csv/reporter are:

  • :locale
  • :rate-unit
  • :duration-unit
  • :filter

JMX and jvisualvm

metrics-clojure also supports JMX reporting, since it’s built into metrics itself.:

(require '[metrics.reporters.jmx :as jmx])

(def JR (jmx/reporter reg {}))
(jmx/start JR)

This will tell metrics to make all metrics available via JMX under metrics domain.

Once this is done, you can open jvisualvm (which you probably already have as it’s included in many Java distributions), connect to a process, and view metrics in the MBeans tab.

Optional arguments to jmx/reporter are:

  • :domain
  • :rate-unit
  • :duration-unit
  • :filter

Note that there are options available to the JMX reporter that are not visible through the Clojure interface. I’m not that familiar with JMX, and didn’t know how to handle things like ObjectNameFactory.

See https://github.com/dropwizard/metrics/blob/master/metrics-core/src/main/java/com/codahale/metrics/JmxReporter.java for the original code.