Codahale Metrics: using @Timed metrics annotation in plain Java

Question

I am trying to add metrics to a plain Java application using codahale metrics. I\'d like to use the @Timed annotation, but it is unclear to me which MetricRegistry it uses,

Answer 1

AOP is overkill and not appropriate for use of @timed, generally speaking.

The default metrics registry writes @timed metrics to a ConcurrentHashMap and does not attach any meaningful listeners.

DropWizard Bootstrap constructor:

/**
 * Creates a new {@link Bootstrap} for the given application.
 * @param application a Dropwizard {@link Application}
 */
public Bootstrap(Application application) {
    this.application = application;
    this.objectMapper = Jackson.newObjectMapper();
    this.bundles = Lists.newArrayList();
    this.configuredBundles = Lists.newArrayList();
    this.commands = Lists.newArrayList();
    this.validatorFactory = Validators.newValidatorFactory();


    // returns new ConcurrentHashMap(); 
    this.metricRegistry = new MetricRegistry(); 


    this.configurationSourceProvider = new FileConfigurationSourceProvider();
    this.classLoader = Thread.currentThread().getContextClassLoader();
    this.configurationFactoryFactory = new DefaultConfigurationFactoryFactory();
}

So you need to build/start/register the appropriate metric registry in order to see results.

Here I use JMX:

@Override
public void initialize(Bootstrap bootstrap) {
    JmxReporter.forRegistry(bootstrap.getMetricRegistry()).build().start();
}

That's all you need to do.

Here's an example of the output (run jconsole against your Java application/server to view JMX results):