DeadlockDetectionTimerTask.java

package com.orbitz.monitoring.lib.timertask;

import com.orbitz.monitoring.api.MonitoringLevel;
import com.orbitz.monitoring.api.monitor.EventMonitor;

import java.lang.management.ManagementFactory;
import java.lang.management.ThreadMXBean;
import java.util.Collection;
import java.util.Collections;

/**
 * Timer task that will fire a monitor of deadlocked
 * threads are detected.
 */
public class DeadlockDetectionTimerTask extends MonitorEmittingTimerTask {
  /**
   * Default constructor. Enables thread contention
   * monitoring.
   */
  public DeadlockDetectionTimerTask() {
    final ThreadMXBean threadBean = ManagementFactory.getThreadMXBean();
    if (threadBean.isThreadContentionMonitoringSupported()) {
      threadBean.setThreadContentionMonitoringEnabled(true);
    }
  }

  public Collection<EventMonitor> emitMonitors() {
    EventMonitor monitor = null;
    final ThreadMXBean threadBean = ManagementFactory.getThreadMXBean();
    if (threadBean.isThreadContentionMonitoringEnabled()) {
      long[] findMonitorDeadlockedThreads = threadBean.findMonitorDeadlockedThreads();
      if (findMonitorDeadlockedThreads != null) {
        monitor = new EventMonitor("JvmStats", MonitoringLevel.ESSENTIAL);
        monitor.set("type", "Thread.Deadlock");
        monitor.set("count", 1);
        monitor.fire();
      }
    }
    return Collections.singleton(monitor);
  }
}