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Java example source code file (MonitorCacheDumpPanel.java)

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

Learn more about this Java project at its project page.

Java - Java tags/keywords

awt, borderlayout, bytearrayoutputstream, gui, javathread, jpanel, jscrollpane, jtextarea, monitor, monitorcachedumppanel, objectheap, objectmonitor, oophandle, printstream, swing, this, util

The MonitorCacheDumpPanel.java Java example source code

/*
 * Copyright (c) 2002, 2007, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code 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 GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

package sun.jvm.hotspot.ui;

import java.awt.*;
import java.io.*;
import javax.swing.*;
import java.util.*;

import sun.jvm.hotspot.memory.*;
import sun.jvm.hotspot.runtime.*;
import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.oops.*;

/** Provides information about monitor cache. */

public class MonitorCacheDumpPanel extends JPanel {
  public MonitorCacheDumpPanel() {
    super();

    setLayout(new BorderLayout());

    // Simple at first
    JScrollPane scroller = new JScrollPane();
    JTextArea textArea = new JTextArea();
    textArea = new JTextArea();
    textArea.setEditable(false);
    textArea.setLineWrap(true);
    textArea.setWrapStyleWord(true);
    scroller.getViewport().add(textArea);
    add(scroller, BorderLayout.CENTER);

    ByteArrayOutputStream bos = new ByteArrayOutputStream();
    PrintStream tty = new PrintStream(bos);
    tty.println("Monitor Cache Dump (not including JVMTI raw monitors):");
    tty.println();
    dumpOn(tty);

    textArea.setText(bos.toString());
  }

  private static void dumpMonitor(PrintStream tty, ObjectMonitor mon, boolean raw) {
    tty.print("ObjectMonitor@" + mon.getAddress());
    if (raw) tty.print("(Raw Monitor)");
    tty.println();
    tty.println("  _header: 0x" + Long.toHexString(mon.header().value()));
    OopHandle obj = mon.object();
    Oop oop = heap.newOop(obj);
    tty.println("  _object: " + obj + ", a " + oop.getKlass().getName().asString());
    Address owner = mon.owner();
    tty.println("  _owner: " + owner);
    if (!raw && owner != null) {
      JavaThread thread = threads.owningThreadFromMonitor(mon);
      if (thread != null) {
        tty.println("    owning thread: " + thread.getThreadName());
        if (!thread.getAddress().equals(owner)) {
          if (!thread.isLockOwned(owner)) {
            tty.println("    WARNING! _owner doesn't fall in " + thread +
                        "'s stack space");
          }
        }
      }
    }
    tty.println("  _count: " + mon.count());
    tty.println("  _waiters: " + mon.waiters());
    tty.println("  _recursions: " + mon.recursions());
  }

  private void dumpOn(PrintStream tty) {
    Iterator i = ObjectSynchronizer.objectMonitorIterator();
    if (i == null) {
      tty.println("This version of HotSpot VM doesn't support monitor cache dump.");
      tty.println("You need 1.4.0_04, 1.4.1_01 or later versions");
      return;
    }
    ObjectMonitor mon;
    while (i.hasNext()) {
      mon = (ObjectMonitor)i.next();
      if (mon.count() != 0 || mon.waiters() != 0 || mon.owner() != null) {
        OopHandle object = mon.object();
        if (object == null) {
          dumpMonitor(tty, mon, true);
        } else {
          dumpMonitor(tty, mon, false);
        }
      }
    }
  }

  private static Threads threads = VM.getVM().getThreads();
  private static ObjectHeap heap = VM.getVM().getObjectHeap();
}

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