1 /* 2 * Copyright (c) 2011, 2016, 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 * @modules java.management 29 * @run main/othervm -Xlog:gc TestFullGCCount 30 */ 31 32 import java.lang.management.GarbageCollectorMXBean; 33 import java.lang.management.ManagementFactory; 34 import java.util.ArrayList; 35 import java.util.HashMap; 36 import java.util.List; 37 38 /* 39 * Originally for a specific failure in CMS, this test now monitors all 40 * collectors for double-counting of collections. 41 */ 42 public class TestFullGCCount { 43 44 static List<GarbageCollectorMXBean> collectors = ManagementFactory.getGarbageCollectorMXBeans(); 45 46 public static void main(String[] args) { 47 int iterations = 20; 48 boolean failed = false; 49 String errorMessage = ""; 50 HashMap<String, List> counts = new HashMap<>(); 51 52 // Prime the collection of count lists for all collectors. 53 for (int i = 0; i < collectors.size(); i++) { 54 GarbageCollectorMXBean collector = collectors.get(i); 55 counts.put(collector.getName(), new ArrayList<>(iterations)); 56 } 57 58 // Perform some gc, record collector counts. 59 for (int i = 0; i < iterations; i++) { 60 System.gc(); 61 addCollectionCount(counts, i); 62 } 63 64 // Check the increments: 65 // Old gen collectors should increase by one, 66 // New collectors may or may not increase. 67 // Any increase >=2 is unexpected. 68 for (String collector : counts.keySet()) { 69 System.out.println("Checking: " + collector); 70 71 for (int i = 0; i < iterations - 1; i++) { 72 List<Long> theseCounts = counts.get(collector); 73 long a = theseCounts.get(i); 74 long b = theseCounts.get(i + 1); 75 if (b - a >= 2) { 76 failed = true; 77 errorMessage += "Collector '" + collector + "' has increment " + (b - a) + 78 " at iteration " + i + "\n"; 79 } 80 } 81 } 82 if (failed) { 83 System.err.println(errorMessage); 84 throw new RuntimeException("FAILED: System.gc collections miscounted."); 85 } 86 System.out.println("Passed."); 87 } 88 89 private static void addCollectionCount(HashMap<String, List> counts, int iteration) { 90 for (int i = 0; i < collectors.size(); i++) { 91 GarbageCollectorMXBean collector = collectors.get(i); 92 List thisList = counts.get(collector.getName()); 93 thisList.add(collector.getCollectionCount()); 94 } 95 } 96 }