Measure and find bottlenecks before they affect your users 1/2

Inspired by a few talks during the last 33rd Degree conference I decided to implement, in one of the applications I develop, metrics which allow developers or operation team monitor running application and possibly detect potential problems early on.

After a quick investigation I decided to use the Metrics framework. What I expected was exposing at least some statistics concerning usage of application components. First of all I would use them during application stress tests to find particular components slowing down the application. After going into production, I imagine that such statistics would be helpful to monitor the running application.

Metrics framework perfectly fits my expectations. It is a Java framework. What is more there are Javascript ports which I am going to use to monitor Node.js server (more about it in one of the next posts).
I decided to integrate the tool with Spring application context using metrics-spring but of course it is possible to use it without Spring.

Here is the Spring application context with Metrics support:

The configuration defining a few beans:

  • metrics-registry is the bean used to register generated metrics; its explicit definition is optional, if not defined new MetricRegistry bean is created
  • annotation-driven element tells that annotations are used to mark methods/beans under monitoring
  • reporter element is used to report gathered statistics to the defined consumers; there are a few reporter implementation provided (jmx, console, slf4j, ganglia, graphite); I decided to use two of them:
    • jmx (JmxReporter) exposing metrics as JMX MBeans; they can be explored using standard tools like jconsole or VisualVM
    • slf4j (Slf4jReporter) logging metrics to an SLF4J logger; period attribute defines the interval used to report statistics to a log file

When configuration is done, it is time to annotate the bean methods which are to be monitored. To do that there is a simple @Timed annotation provided:

Using that simple configuration you get JMX MBeans exposed providing a nice set of metrics:
What is more, if any statistic is clicked an online chart is presented:



Besides the JMX reporter there is also the SLF4J reported defined, which logs the following pieces of information:



Except JMX or SLF4J reporting more sophisticated tools can be used to consume statistics provided my Metrics. I would recommend trying Ganglia or Graphite as there are reporters provided for those consumers (GangliaReporter and GraphiteReporter).

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