1 /*
   2  * Copyright (c) 2011, 2018, 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 TestFullGCCount.java
  26  * @bug 7072527
  27  * @summary CMS: JMM GC counters overcount in some cases
  28  * @requires !(vm.gc.ConcMarkSweep & vm.opt.ExplicitGCInvokesConcurrent == true)
  29  * @requires !(vm.gc == "Shenandoah" & !(vm.opt.ExplicitGCInvokesConcurrent == false))
  30  * @modules java.management
  31  * @run main/othervm -Xlog:gc TestFullGCCount
  32  */
  33 
  34 import java.lang.management.GarbageCollectorMXBean;
  35 import java.lang.management.ManagementFactory;
  36 import java.util.ArrayList;
  37 import java.util.HashMap;
  38 import java.util.List;
  39 
  40 /*
  41  * Originally for a specific failure in CMS, this test now monitors all
  42  * collectors for double-counting of collections.
  43  */
  44 public class TestFullGCCount {
  45 
  46     static List<GarbageCollectorMXBean> collectors = ManagementFactory.getGarbageCollectorMXBeans();
  47 
  48     public static void main(String[] args) {
  49         int iterations = 20;
  50         boolean failed = false;
  51         String errorMessage = "";
  52         HashMap<String, List> counts = new HashMap<>();
  53 
  54         // Prime the collection of count lists for all collectors.
  55         for (int i = 0; i < collectors.size(); i++) {
  56             GarbageCollectorMXBean collector = collectors.get(i);
  57             counts.put(collector.getName(), new ArrayList<>(iterations));
  58         }
  59 
  60         // Perform some gc, record collector counts.
  61         for (int i = 0; i < iterations; i++) {
  62             System.gc();
  63             addCollectionCount(counts, i);
  64         }
  65 
  66         // Check the increments:
  67         //   Old gen collectors should increase by one,
  68         //   New collectors may or may not increase.
  69         //   Any increase >=2 is unexpected.
  70         for (String collector : counts.keySet()) {
  71             System.out.println("Checking: " + collector);
  72 
  73             for (int i = 0; i < iterations - 1; i++) {
  74                 List<Long> theseCounts = counts.get(collector);
  75                 long a = theseCounts.get(i);
  76                 long b = theseCounts.get(i + 1);
  77                 if (b - a >= 2) {
  78                     failed = true;
  79                     errorMessage += "Collector '" + collector + "' has increment " + (b - a) +
  80                                     " at iteration " + i + "\n";
  81                 }
  82             }
  83         }
  84         if (failed) {
  85             System.err.println(errorMessage);
  86             throw new RuntimeException("FAILED: System.gc collections miscounted.");
  87         }
  88         System.out.println("Passed.");
  89     }
  90 
  91     private static void addCollectionCount(HashMap<String, List> counts, int iteration) {
  92         for (int i = 0; i < collectors.size(); i++) {
  93             GarbageCollectorMXBean collector = collectors.get(i);
  94             List thisList = counts.get(collector.getName());
  95             thisList.add(collector.getCollectionCount());
  96         }
  97     }
  98 }