http://metrics.dropwizard.io/metrics-jvm: A set of classes which allow you to monitor critical aspects of your Java Virtual Machine using Metrics.
  • Coda Hale
  • Ryan Tenney
  • Artem Prigoda 
package com.codahale.metrics.jvm;

import com.codahale.metrics.RatioGauge;
import com.sun.management.UnixOperatingSystemMXBean;

import java.lang.management.ManagementFactory;
import java.lang.management.OperatingSystemMXBean;


A gauge for the ratio of used to total file descriptors.

/**
 * A gauge for the ratio of used to total file descriptors.
 */
public class FileDescriptorRatioGauge extends RatioGauge {
    private final OperatingSystemMXBean os;

    
Creates a new gauge using the platform OS bean.

/**
     * Creates a new gauge using the platform OS bean.
     */
    public FileDescriptorRatioGauge() {
        this(ManagementFactory.getOperatingSystemMXBean());
    }

    
Creates a new gauge using the given OS bean.

Params:
/**
     * Creates a new gauge using the given OS bean.
     *
     * @param os an {@link OperatingSystemMXBean}
     */
    public FileDescriptorRatioGauge(OperatingSystemMXBean os) {
        this.os = os;
    }

    @Override
    protected Ratio getRatio() {
        if (os instanceof UnixOperatingSystemMXBean) {
            final UnixOperatingSystemMXBean unixOs = (UnixOperatingSystemMXBean) os;
            return Ratio.of(unixOs.getOpenFileDescriptorCount(), unixOs.getMaxFileDescriptorCount());
        } else {
            return Ratio.of(Double.NaN, Double.NaN);
        }
    }
}