| /* |
| * Copyright (c) 2004, 2013, 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.tools; |
| |
| import sun.jvm.hotspot.debugger.JVMDebugger; |
| |
| import sun.jvm.hotspot.oops.*; |
| import sun.jvm.hotspot.utilities.SystemDictionaryHelper; |
| |
| import java.util.ArrayList; |
| import java.util.Collections; |
| import java.util.Comparator; |
| import java.util.HashMap; |
| |
| /* |
| * Iterates over the queue of object pending finalization and prints a |
| * summary of these objects in the form of a histogram. |
| */ |
| public class FinalizerInfo extends Tool { |
| |
| public FinalizerInfo() { |
| super(); |
| } |
| |
| public FinalizerInfo(JVMDebugger d) { |
| super(d); |
| } |
| |
| @Override |
| public String getName() { |
| return "finalizerInfo"; |
| } |
| |
| public static void main(String[] args) { |
| FinalizerInfo finfo = new FinalizerInfo(); |
| finfo.execute(args); |
| } |
| |
| public void run() { |
| /* |
| * The implementation here has a dependency on the implementation of |
| * java.lang.ref.Finalizer. If the Finalizer implementation changes it's |
| * possible this method will require changes too. We looked into using |
| * ObjectReader to deserialize the objects from the target VM but as |
| * there aren't any public methods to traverse the queue it means using |
| * reflection which will also tie us to the implementation. |
| * |
| * The assumption here is that Finalizer.queue is the ReferenceQueue |
| * with the objects awaiting finalization. The ReferenceQueue queueLength |
| * is the number of objects in the queue, and 'head' is the head of the |
| * queue. |
| */ |
| InstanceKlass ik = |
| SystemDictionaryHelper.findInstanceKlass("java.lang.ref.Finalizer"); |
| final Oop[] queueref = new Oop[1]; |
| ik.iterateStaticFields(new DefaultOopVisitor() { |
| public void doOop(OopField field, boolean isVMField) { |
| String name = field.getID().getName(); |
| if (name.equals("queue")) { |
| queueref[0] = field.getValue(getObj()); |
| } |
| } |
| }); |
| Oop queue = queueref[0]; |
| |
| InstanceKlass k = (InstanceKlass) queue.getKlass(); |
| |
| LongField queueLengthField = (LongField) k.findField("queueLength", "J"); |
| long queueLength = queueLengthField.getValue(queue); |
| |
| OopField headField = (OopField) k.findField("head", "Ljava/lang/ref/Reference;"); |
| Oop head = headField.getValue(queue); |
| |
| System.out.println("Number of objects pending for finalization: " + queueLength); |
| |
| /* |
| * If 'head' is non-NULL then it is the head of a list of References. |
| * We iterate over the list (end of list is when head.next == head) |
| */ |
| if (head != null) { |
| k = (InstanceKlass) head.getKlass(); |
| OopField referentField = |
| (OopField) k.findField("referent", "Ljava/lang/Object;"); |
| OopField nextField = |
| (OopField) k.findField("next", "Ljava/lang/ref/Reference;"); |
| |
| HashMap map = new HashMap(); |
| for (;;) { |
| Oop referent = referentField.getValue(head); |
| |
| Klass klass = referent.getKlass(); |
| if (!map.containsKey(klass)) { |
| map.put(klass, new ObjectHistogramElement(klass)); |
| } |
| ((ObjectHistogramElement)map.get(klass)).updateWith(referent); |
| |
| Oop next = nextField.getValue(head); |
| if (next == null || next.equals(head)) break; |
| head = next; |
| } |
| |
| /* |
| * Sort results - decending order by total size |
| */ |
| ArrayList list = new ArrayList(); |
| list.addAll(map.values()); |
| Collections.sort(list, new Comparator() { |
| public int compare(Object o1, Object o2) { |
| return ((ObjectHistogramElement)o1).compare((ObjectHistogramElement)o2); |
| } |
| }); |
| |
| /* |
| * Print summary of objects in queue |
| */ |
| System.out.println(""); |
| System.out.println("Count" + "\t" + "Class description"); |
| System.out.println("-------------------------------------------------------"); |
| for (int i=0; i<list.size(); i++) { |
| ObjectHistogramElement e = (ObjectHistogramElement)list.get(i); |
| System.out.println(e.getCount() + "\t" + e.getDescription()); |
| } |
| } |
| |
| } |
| } |