How to retrieve the number of full garbage collections in Java using JMX?

6 months ago

Liam

2 minutes

One way to implement in Java using JMX (Java Management Extensions) is to get the number of Full GC occurrences through MBeans.

Create an MBean interface with the following code that includes a method to retrieve the number of Full GC occurrences:

public interface GCStatsMBean {
    long getFullGCCount();
}

Create a class implementing the MBean interface that includes a method for retrieving the number of Full GC occurrences.

public class GCStats implements GCStatsMBean {
    private long fullGCCount = 0;

    public long getFullGCCount() {
        return fullGCCount;
    }

    public void incrementFullGCCount() {
        fullGCCount++;
    }
}

public static void main(String[] args) throws Exception {
    MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
    GCStats gcStats = new GCStats();
    ObjectName name = new ObjectName("com.example:type=GCStats");
    mbs.registerMBean(gcStats, name);

    // 监听GC事件，并在发生Full GC时调用incrementFullGCCount方法
    NotificationEmitter emitter = (NotificationEmitter) ManagementFactory.getGarbageCollectorMXBeans().get(0);
    emitter.addNotificationListener(new NotificationListener() {
        @Override
        public void handleNotification(Notification notification, Object handback) {
            if (notification.getType().equals(GarbageCollectionNotificationInfo.GARBAGE_COLLECTION_NOTIFICATION)) {
                GarbageCollectionNotificationInfo info = GarbageCollectionNotificationInfo.from((CompositeData) notification.getUserData());
                if (info.getGcAction().equals("end of major GC")) {
                    gcStats.incrementFullGCCount();
                }
            }
        }
    }, null, null);

    // 等待程序运行
    Thread.sleep(Long.MAX_VALUE);
}

We can retrieve the number of Full GCs in JMX by calling the getFullGCCount method of GCStatsMBean.