1 /* 2 * Copyright (c) 2011, 2013, 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:+PrintGC TestFullGCCount 29 */ 30 import java.util.*; 31 import java.lang.management.*; 32 33 /* 34 * Originally for a specific failure in CMS, this test now monitors all 35 * collectors for double-counting of collections. 36 */ 37 public class TestFullGCCount { 38 39 static List<GarbageCollectorMXBean> collectors = ManagementFactory.getGarbageCollectorMXBeans(); 40 41 public static void main(String[] args) { 42 int iterations = 20; 43 boolean failed = false; 44 String errorMessage = ""; 45 HashMap<String, List> counts = new HashMap<String, List>(); 46 47 // Prime the collection of count lists for all collectors. 48 for (int i = 0; i < collectors.size(); i++) { 49 GarbageCollectorMXBean collector = collectors.get(i); 50 counts.put(collector.getName(), new ArrayList<Long>(iterations)); 51 } 52 53 // Perform some gc, record collector counts. 54 for (int i = 0; i < iterations; i++) { 55 System.gc(); 56 addCollectionCount(counts, i); 57 } 58 59 // Check the increments: 60 // Old gen collectors should increase by one, 61 // New collectors may or may not increase. 62 // Any increase >=2 is unexpected. 63 for (String collector : counts.keySet()) { 64 System.out.println("Checking: " + collector); 65 66 for (int i = 0; i < iterations - 1; i++) { 67 List<Long> theseCounts = counts.get(collector); 68 long a = theseCounts.get(i); 69 long b = theseCounts.get(i + 1); 70 if (b - a >= 2) { 71 failed = true; 72 errorMessage += "Collector '" + collector + "' has increment " + (b - a) + 73 " at iteration " + i + "\n"; 74 } 75 } 76 } 77 if (failed) { 78 System.err.println(errorMessage); 79 throw new RuntimeException("FAILED: System.gc collections miscounted."); 80 } 81 System.out.println("Passed."); 82 } 83 84 private static void addCollectionCount(HashMap<String, List> counts, int iteration) { 85 for (int i = 0; i < collectors.size(); i++) { 86 GarbageCollectorMXBean collector = collectors.get(i); 87 List thisList = counts.get(collector.getName()); 88 thisList.add(collector.getCollectionCount()); 89 } 90 } 91 }