Analyzer.java

/*
 * Analyzer.java
 *
 * This file is part of TDA - Thread Dump Analysis Tool.
 *
 * Foobar is free software; you can redistribute it and/or modify
 * it under the terms of the Lesser GNU General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or
 * (at your option) any later version.
 *
 * Foobar is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * Lesser GNU General Public License for more details.
 *
 * You should have received a copy of the Lesser GNU General Public License
 * along with Foobar; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * $Id: Analyzer.java,v 1.3 2008-01-28 09:29:34 irockel Exp $
 */

package com.pironet.tda;

import java.io.Serializable;

/**
 * analyze the given thread dump.
 * 
 * @author irockel
 */
public class Analyzer implements Serializable {
	ThreadDumpInfo tdi;

	/**
	 * generate a dump analyzer for the given thread dump.
	 * @param tdi the thread dump to analyze.
	 */
	public Analyzer(ThreadDumpInfo tdi) {
		this.tdi = tdi;
	}

	/**
	 * analyze the given data and generate htmlified hints
	 * @return html-text containing hints, empty strings if no hints can
	 *         be given.
	 */
	public String analyzeDump() {
		// check for possible hot spots concerning this thread dump

		StringBuffer statData = new StringBuffer();
		int deadlocks = tdi.getDeadlocks() == null ? 0 : tdi.getDeadlocks().getNodeCount();
		int threadCount = tdi.getThreads() == null ? 0 : tdi.getThreads().getNodeCount();
		int waiting = tdi.getWaitingThreads() == null ? 0 : tdi.getWaitingThreads().getNodeCount();
		int sleeping = tdi.getSleepingThreads() == null ? 0 : tdi.getSleepingThreads().getNodeCount();

		int overallThreadsWaitingWithoutLocks = tdi.getOverallThreadsWaitingWithoutLocksCount();
		int monitorsWithoutLocksCount = tdi.getMonitorsWithoutLocks() == null ? 0 : tdi.getMonitorsWithoutLocks().getNodeCount();

		// check if a lot of threads are in state "waiting"
		if ((deadlocks == 0) && (threadCount > 0) && ((waiting / (threadCount / 100.0)) > 10.0)) {
			statData.append("<tr bgcolor=\"#ffffff\"<td></td></tr>");
			statData.append("<tr bgcolor=\"#cccccc\"><td colspan=2><font face=System " +
					"><p>" + (int) (waiting / (threadCount / 100.0)) + "% of all threads are waiting for a monitor to become available again.</p><br>");
			statData.append("This might indicate a congestion or even a deadlock. If a monitor doesn't have a locking thread, it might be<br>");
			statData.append("hold by some external resource or system thread. You should check the <a href=\"wait://\">waiting threads</a>.<br></td></tr>");
		} else if (deadlocks > 0) {
			statData.append("<tr bgcolor=\"#ffffff\"<td></td></tr>");
			statData.append("<tr bgcolor=\"#cccccc\"><td colspan=2><font face=System " +
					"><p>The JVM has detected " + deadlocks + " deadlock(s) in the thread dump. You should check the <br><a href=\"dead://\">deadlocks</a> for further information.</p><br>");
		}

		// check if a lot of threads are in state "waiting"
		if ((threadCount > 0) && ((sleeping / (threadCount / 100.0)) > 25.0)) {
			statData.append("<tr bgcolor=\"#ffffff\"<td></td></tr>");
			statData.append("<tr bgcolor=\"#cccccc\"><td colspan=2><font face=System" +
					"><p>" + (int) (sleeping / (threadCount / 100.0)) + "% of all threads are sleeping on a monitor.</p><br>");
			statData.append("This might indicate they are waiting for some external resource (e.g. database) which is overloaded<br>");
			statData.append("or not available or are just waiting to get to do something (idle threads).<br>");
			statData.append("You should check the <a href=\"sleep://\">sleeping threads</a> with a filter excluding all idle threads.</td></tr>");
		}

		// display an info if there are monitors without locking threads
		if (monitorsWithoutLocksCount > 0) {
			statData.append("<tr bgcolor=\"#ffffff\"<td></td></tr>");
			statData.append("<tr bgcolor=\"#cccccc\"><td colspan=2><font face=System" +
					"><p>This thread dump contains monitors without a locking thread information.<br>");
			statData.append("This means, the monitor is hold by a system thread or some external resource.</p<br>");
			statData.append("You should check the monitors without locking threads for more information.<br></td></tr>");
		}

		// check for indications for running garbage collector
		if ((threadCount > 0) && (overallThreadsWaitingWithoutLocks / (threadCount / 100.0) > 50.0)) {
			statData.append("<tr bgcolor=\"#ffffff\"<td></td></tr>");
			statData.append("<tr bgcolor=\"#cccccc\"><td colspan=2><font face=System " +
					"<p>" + (int) (overallThreadsWaitingWithoutLocks / (threadCount / 100.0)) + "% of all threads are waiting for a monitor without an application ");
			statData.append("thread holding it.<br> This indicates a congestion. It is very likely the garbage collector is running ");
			statData.append("and is blocking the monitors.</p<br>");
			statData.append("You should check the monitors without locking threads for more information on the blocked threads.<br>");
			statData.append("You also should analyze the garbage collector behaviour. Go to the ");
			statData.append("<a href=\"http://www.tagtraum.com/gcviewer.html\">GCViewer-Homepage</a> for more<br>");
			statData.append(" information on how to do this.</td></tr>");
		}

		return statData.toString();
	}
}