通过 servlet 访问 Dropwizard JVM 指标的问题

Question

I'm adding Dropwizard Metrics to a web application. I'm using the metrics servlet to retrieve the data. However, I cannot get the JVM details to be returned.

I've set the following on the MetricRegistry

metrics.register("jvm.memory", new MemoryUsageGaugeSet());
metrics.register("jvm.gc", new GarbageCollectorMetricSet());
metrics.register("jvm.attribute", new JvmAttributeGaugeSet());
metrics.register("jvm.threads", new ThreadStatesGaugeSet());
metrics.register("jvm.buffers", new BufferPoolMetricSet(ManagementFactory
                    .getPlatformMBeanServer()));
metrics.register("jvm.classloader", new ClassLoadingGaugeSet());
metrics.register("jvm.filedescriptor", new FileDescriptorRatioGauge());

According to the following javadoc, it says the Metrics Servlet takes a parameter. https://metrics.dropwizard.io/4.1.2/manual/servlets.html

MetricsServlet
.....
MetricsServlet also takes an initialization parameter, show-jvm-metrics, which if "false" will disable the outputting of JVM-level information in the JSON object.

I've done this but I still am not getting the JVM stats returned. The docs seem to infer that it should be true by default.

<servlet>
        <servlet-name>metrics</servlet-name>
        <servlet-class>com.codahale.metrics.servlets.MetricsServlet</servlet-class>
        <init-param>
            <param-name>show-jvm-metrics</param-name>
            <param-value>true</param-value>
        </init-param>
    </servlet>

Am I missing another step?

Thanks

Answer 1

Ok, so turns out this is correct. No missing step. For some reason after trying it again today the exact same code worked with no changes. Go figure.