1 /*
   2  * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 /*
  25  * @test TestFullGCount.java
  26  * @bug 7072527
  27  * @summary CMS: JMM GC counters overcount in some cases
  28  * @run main/othervm -XX:+UseConcMarkSweepGC TestFullGCCount
  29  *
  30  */
  31 import java.util.*;
  32 import java.lang.management.*;
  33 
  34 public class TestFullGCCount {
  35 
  36     public String collectorName = "ConcurrentMarkSweep";
  37 
  38     public static void main(String [] args) {
  39 
  40         TestFullGCCount t = null;
  41         if (args.length==2) {
  42             t = new TestFullGCCount(args[0], args[1]);
  43         } else {
  44             t = new TestFullGCCount();
  45         }
  46         System.out.println("Monitoring collector: " + t.collectorName);
  47         t.run();
  48     }
  49 
  50     public TestFullGCCount(String pool, String collector) {
  51         collectorName = collector;
  52     }
  53 
  54     public TestFullGCCount() {
  55     }
  56 
  57     public void run() {
  58         int count = 0;
  59         int iterations = 20;
  60         long counts[] = new long[iterations];
  61         boolean diffAlways2 = true; // assume we will fail
  62 
  63         for (int i=0; i<iterations; i++) {
  64             System.gc();
  65             counts[i] = getCollectionCount();
  66             if (i>0) {
  67                 if (counts[i] - counts[i-1] != 2) {
  68                     diffAlways2 = false;
  69                 }
  70             }
  71         }
  72         if (diffAlways2) {
  73             throw new RuntimeException("FAILED: System.gc must be incrementing count twice.");
  74         }
  75         System.out.println("Passed.");
  76     }
  77 
  78     private long getCollectionCount() {
  79         long count = 0;
  80         List<MemoryPoolMXBean> pools = ManagementFactory.getMemoryPoolMXBeans();
  81         List<GarbageCollectorMXBean> collectors = ManagementFactory.getGarbageCollectorMXBeans();
  82         for (int i=0; i<collectors.size(); i++) {
  83             GarbageCollectorMXBean collector = collectors.get(i);
  84             String name = collector.getName();
  85             if (name.contains(collectorName)) {
  86                 System.out.println(name + ": collection count = "
  87                                    + collector.getCollectionCount());
  88                 count = collector.getCollectionCount();
  89             }
  90         }
  91         return count;
  92     }
  93 
  94 }
  95