Java tutorial
/* * @(#)JTop.java 1.5 06/05/08 * * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * -Redistribution of source code must retain the above copyright notice, this * list of conditions and the following disclaimer. * * -Redistribution in binary form must reproduce the above copyright notice, * this list of conditions and the following disclaimer in the documentation * and/or other materials provided with the distribution. * * Neither the name of Sun Microsystems, Inc. or the names of contributors may * be used to endorse or promote products derived from this software without * specific prior written permission. * * This software is provided "AS IS," without a warranty of any kind. ALL * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN") * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. * * You acknowledge that this software is not designed, licensed or intended * for use in the design, construction, operation or maintenance of any * nuclear facility. */ /* * @(#)JTop.java 1.5 06/05/08 * * Example of using the java.lang.management API to sort threads * by CPU usage. * * JTop class can be run as a standalone application. * It first establishs a connection to a target VM specified * by the given hostname and port number where the JMX agent * to be connected. It then polls for the thread information * and the CPU consumption of each thread to display every 2 * seconds. * * It is also used by JTopPlugin which is a JConsolePlugin * that can be used with JConsole (see README.txt). The JTop * GUI will be added as a JConsole tab by the JTop plugin. * * @see com.sun.tools.jconsole.JConsolePlugin * * @author Mandy Chung */ import static java.lang.management.ManagementFactory.THREAD_MXBEAN_NAME; import static java.lang.management.ManagementFactory.newPlatformMXBeanProxy; import java.awt.BorderLayout; import java.awt.Dimension; import java.awt.GridLayout; import java.io.IOException; import java.lang.management.ThreadInfo; import java.lang.management.ThreadMXBean; import java.net.MalformedURLException; import java.text.NumberFormat; import java.util.ArrayList; import java.util.Collections; import java.util.List; import java.util.Map; import java.util.Set; import java.util.SortedMap; import java.util.Timer; import java.util.TimerTask; import java.util.TreeMap; import java.util.concurrent.ExecutionException; import javax.management.MBeanServerConnection; import javax.management.remote.JMXConnector; import javax.management.remote.JMXConnectorFactory; import javax.management.remote.JMXServiceURL; import javax.swing.JComponent; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.JTable; import javax.swing.SwingUtilities; import javax.swing.SwingWorker; import javax.swing.border.EmptyBorder; import javax.swing.table.AbstractTableModel; import javax.swing.table.DefaultTableCellRenderer; /** * JTop is a JPanel to display thread's name, CPU time, and its state in a * table. */ public class JTop extends JPanel { private MBeanServerConnection server; private ThreadMXBean tmbean; private MyTableModel tmodel; public JTop() { super(new GridLayout(1, 0)); tmodel = new MyTableModel(); JTable table = new JTable(tmodel); table.setPreferredScrollableViewportSize(new Dimension(500, 300)); // Set the renderer to format Double table.setDefaultRenderer(Double.class, new DoubleRenderer()); // Add some space table.setIntercellSpacing(new Dimension(6, 3)); table.setRowHeight(table.getRowHeight() + 4); // Create the scroll pane and add the table to it. JScrollPane scrollPane = new JScrollPane(table); // Add the scroll pane to this panel. add(scrollPane); } // Set the MBeanServerConnection object for communicating // with the target VM public void setMBeanServerConnection(MBeanServerConnection mbs) { this.server = mbs; try { this.tmbean = newPlatformMXBeanProxy(server, THREAD_MXBEAN_NAME, ThreadMXBean.class); } catch (IOException e) { e.printStackTrace(); } if (!tmbean.isThreadCpuTimeSupported()) { System.err.println("This VM does not support thread CPU time monitoring"); } else { tmbean.setThreadCpuTimeEnabled(true); } } class MyTableModel extends AbstractTableModel { private String[] columnNames = { "ThreadName", "CPU(sec)", "State" }; // List of all threads. The key of each entry is the CPU time // and its value is the ThreadInfo object with no stack trace. private List<Map.Entry<Long, ThreadInfo>> threadList = Collections.EMPTY_LIST; public MyTableModel() { } public int getColumnCount() { return columnNames.length; } public int getRowCount() { return threadList.size(); } public String getColumnName(int col) { return columnNames[col]; } public Object getValueAt(int row, int col) { Map.Entry<Long, ThreadInfo> me = threadList.get(row); switch (col) { case 0: // Column 0 shows the thread name return me.getValue().getThreadName(); case 1: // Column 1 shows the CPU usage long ns = me.getKey().longValue(); double sec = ns / 1000000000; return new Double(sec); case 2: // Column 2 shows the thread state return me.getValue().getThreadState(); default: return null; } } public Class getColumnClass(int c) { return getValueAt(0, c).getClass(); } void setThreadList(List<Map.Entry<Long, ThreadInfo>> list) { threadList = list; } } /** * Get the thread list with CPU consumption and the ThreadInfo for each thread * sorted by the CPU time. */ private List<Map.Entry<Long, ThreadInfo>> getThreadList() { // Get all threads and their ThreadInfo objects // with no stack trace long[] tids = tmbean.getAllThreadIds(); ThreadInfo[] tinfos = tmbean.getThreadInfo(tids); // build a map with key = CPU time and value = ThreadInfo SortedMap<Long, ThreadInfo> map = new TreeMap<Long, ThreadInfo>(); for (int i = 0; i < tids.length; i++) { long cpuTime = tmbean.getThreadCpuTime(tids[i]); // filter out threads that have been terminated if (cpuTime != -1 && tinfos[i] != null) { map.put(new Long(cpuTime), tinfos[i]); } } // build the thread list and sort it with CPU time // in decreasing order Set<Map.Entry<Long, ThreadInfo>> set = map.entrySet(); List<Map.Entry<Long, ThreadInfo>> list = new ArrayList<Map.Entry<Long, ThreadInfo>>(set); Collections.reverse(list); return list; } /** * Format Double with 4 fraction digits */ class DoubleRenderer extends DefaultTableCellRenderer { NumberFormat formatter; public DoubleRenderer() { super(); setHorizontalAlignment(JLabel.RIGHT); } public void setValue(Object value) { if (formatter == null) { formatter = NumberFormat.getInstance(); formatter.setMinimumFractionDigits(4); } setText((value == null) ? "" : formatter.format(value)); } } // SwingWorker responsible for updating the GUI // // It first gets the thread and CPU usage information as a // background task done by a worker thread so that // it will not block the event dispatcher thread. // // When the worker thread finishes, the event dispatcher // thread will invoke the done() method which will update // the UI. class Worker extends SwingWorker<List<Map.Entry<Long, ThreadInfo>>, Object> { private MyTableModel tmodel; Worker(MyTableModel tmodel) { this.tmodel = tmodel; } // Get the current thread info and CPU time public List<Map.Entry<Long, ThreadInfo>> doInBackground() { return getThreadList(); } // fire table data changed to trigger GUI update // when doInBackground() is finished protected void done() { try { // Set table model with the new thread list tmodel.setThreadList(get()); // refresh the table model tmodel.fireTableDataChanged(); } catch (InterruptedException e) { } catch (ExecutionException e) { } } } // Return a new SwingWorker for UI update public SwingWorker<?, ?> newSwingWorker() { return new Worker(tmodel); } public static void main(String[] args) throws Exception { // Validate the input arguments if (args.length != 1) { usage(); } String[] arg2 = args[0].split(":"); if (arg2.length != 2) { usage(); } String hostname = arg2[0]; int port = -1; try { port = Integer.parseInt(arg2[1]); } catch (NumberFormatException x) { usage(); } if (port < 0) { usage(); } // Create the JTop Panel final JTop jtop = new JTop(); // Set up the MBeanServerConnection to the target VM MBeanServerConnection server = connect(hostname, port); jtop.setMBeanServerConnection(server); // A timer task to update GUI per each interval TimerTask timerTask = new TimerTask() { public void run() { // Schedule the SwingWorker to update the GUI jtop.newSwingWorker().execute(); } }; // Create the standalone window with JTop panel // by the event dispatcher thread SwingUtilities.invokeAndWait(new Runnable() { public void run() { createAndShowGUI(jtop); } }); // refresh every 2 seconds Timer timer = new Timer("JTop Sampling thread"); timer.schedule(timerTask, 0, 2000); } // Establish a connection with the remote application // // You can modify the urlPath to the address of the JMX agent // of your application if it has a different URL. // // You can also modify the following code to take // username and password for client authentication. private static MBeanServerConnection connect(String hostname, int port) { // Create an RMI connector client and connect it to // the RMI connector server String urlPath = "/jndi/rmi://" + hostname + ":" + port + "/jmxrmi"; MBeanServerConnection server = null; try { JMXServiceURL url = new JMXServiceURL("rmi", "", 0, urlPath); JMXConnector jmxc = JMXConnectorFactory.connect(url); server = jmxc.getMBeanServerConnection(); } catch (MalformedURLException e) { // should not reach here } catch (IOException e) { System.err.println("\nCommunication error: " + e.getMessage()); System.exit(1); } return server; } private static void usage() { System.out.println("Usage: java JTop <hostname>:<port>"); System.exit(1); } /** * Create the GUI and show it. For thread safety, this method should be * invoked from the event-dispatching thread. */ private static void createAndShowGUI(JPanel jtop) { // Create and set up the window. JFrame frame = new JFrame("JTop"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // Create and set up the content pane. JComponent contentPane = (JComponent) frame.getContentPane(); contentPane.add(jtop, BorderLayout.CENTER); contentPane.setOpaque(true); // content panes must be opaque contentPane.setBorder(new EmptyBorder(12, 12, 12, 12)); frame.setContentPane(contentPane); // Display the window. frame.pack(); frame.setVisible(true); } }