ActiveMQ example source code file (ThreadExplorer.java)

This example ActiveMQ source code file (ThreadExplorer.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - ActiveMQ tags/keywords

entering, group, logger, matcher, pattern, regex, string, string, stringbuffer, stringbuffer, thread, thread, threaddeath, threaddeath, threadexplorer

The ActiveMQ ThreadExplorer.java source code

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.activemq.bugs.embedded;

import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.log4j.Logger;

public class ThreadExplorer
{
    static Logger logger = Logger.getLogger(ThreadExplorer.class);

    public static Thread[] listThreads()
    {

        int nThreads = Thread.activeCount();
        Thread ret[] = new Thread[nThreads];

        Thread.enumerate(ret);

        return ret;

    }

    /**
     * Helper function to access a thread per name (ignoring case)
     * 
     * @param name
     * @return
     */
    public static Thread fetchThread(String name)
    {
        Thread[] threadArray = listThreads();
        // for (Thread t : threadArray)
        for (int i = 0; i < threadArray.length; i++)
        {
            Thread t = threadArray[i];
            if (t.getName().equalsIgnoreCase(name))
                return t;
        }
        return null;
    }

    /**
     * Allow for killing threads
     * 
     * @param threadName
     * @param isStarredExp
     *            (regular expressions with *)
     */
    @SuppressWarnings("deprecation")
    public static int kill(String threadName, boolean isStarredExp, String motivation)
    {
        String me = "ThreadExplorer.kill: ";
        if (logger.isDebugEnabled())
        {
            logger.debug("Entering " + me + " with " + threadName + " isStarred: " + isStarredExp);
        }
        int ret = 0;
        Pattern mypattern = null;
        if (isStarredExp)
        {
            String realreg = threadName.toLowerCase().replaceAll("\\*", "\\.\\*");
            mypattern = Pattern.compile(realreg);

        }
        Thread[] threads = listThreads();
        for (int i = 0; i < threads.length; i++)
        {
            Thread thread = threads[i];
            if (thread == null)
                continue;
            // kill the thread unless it is not current thread
            boolean matches = false;

            if (isStarredExp)
            {
                Matcher matcher = mypattern.matcher(thread.getName().toLowerCase());
                matches = matcher.matches();
            }
            else
            {
                matches = (thread.getName().equalsIgnoreCase(threadName));
            }
            if (matches && (Thread.currentThread() != thread) && !thread.getName().equals("main"))
            {
                if (logger.isInfoEnabled())
                    logger.info("Killing thread named [" + thread.getName() + "]"); // , removing its uncaught
                // exception handler to
                // avoid ThreadDeath
                // exception tracing
                // "+motivation );

                ret++;

                // PK leaving uncaught exception handler otherwise master push
                // cannot recover from this error
                // thread.setUncaughtExceptionHandler(null);
                try
                {
                    thread.stop();
                }
                catch (ThreadDeath e)
                {
                    logger.warn("Thread already death.", e);
                }

            }
        }
        return ret;
    }

    public static String show(String title)
    {
        StringBuffer out = new StringBuffer();
        Thread[] threadArray = ThreadExplorer.listThreads();

        out.append(title + "\n");
        for (int i = 0; i < threadArray.length; i++)
        {
            Thread thread = threadArray[i];

            if (thread != null)
            {
                out.append("* [" + thread.getName() + "] " + (thread.isDaemon() ? "(Daemon)" : "")
                        + " Group: " + thread.getThreadGroup().getName() + "\n");
            }
            else
            {
                out.append("* ThreadDeath: " + thread + "\n");
            }

        }
        return out.toString();
    }

    public static int active()
    {
        int count = 0;
        Thread[] threadArray = ThreadExplorer.listThreads();

        for (int i = 0; i < threadArray.length; i++)
        {
            Thread thread = threadArray[i];
            if (thread != null)
            {
                count++;
            }
        }

        return count;
    }

}