1 /*
   2  * Copyright (c) 2017, Red Hat, Inc. All rights reserved.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This code is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  11  * version 2 for more details (a copy is included in the LICENSE file that
  12  * accompanied this code).
  13  *
  14  * You should have received a copy of the GNU General Public License version
  15  * 2 along with this work; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * questions.
  21  *
  22  */
  23 
  24 public class TestHeapDump {
  25 
  26     private static final int NUM_ITER = 10000;
  27 
  28     private static final int ARRAY_SIZE = 1000;
  29 
  30     private static final int EXPECTED_OBJECTS =
  31             ARRAY_SIZE +   // array reachable from instance field
  32                     1 +            // static field root
  33                     1;             // local field root
  34 
  35     static {
  36         try {
  37             System.loadLibrary("TestHeapDump");
  38         } catch (UnsatisfiedLinkError ule) {
  39             System.err.println("Could not load TestHeapDump library");
  40             System.err.println("java.library.path: "
  41                     + System.getProperty("java.library.path"));
  42             throw ule;
  43         }
  44     }
  45 
  46     native static int heapdump(Class<?> filterClass);
  47 
  48     public static void main(String args[]) {
  49         new TestHeapDump().run();
  50     }
  51 
  52     // This root needs to be discovered
  53     static Object root = new TestObject();
  54 
  55     // This field needs to be discovered
  56     TestObject[] array;
  57 
  58     public void run() {
  59         array = new TestObject[ARRAY_SIZE];
  60         for (int i = 0; i < ARRAY_SIZE; i++) {
  61             array[i] = new TestObject();
  62         }
  63         TestObject localRoot = new TestObject();
  64         for (int i = 0; i < NUM_ITER; i++) {
  65             int numObjs = heapdump(TestObject.class);
  66             if (numObjs != EXPECTED_OBJECTS) {
  67                 throw new RuntimeException("Expected " + EXPECTED_OBJECTS + " objects, but got " + numObjs);
  68             }
  69         }
  70     }
  71 
  72     // We look for the instances of this class during the heap scan
  73     public static class TestObject {}
  74 }