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 * @comment Shenandoah has "ExplicitGCInvokesConcurrent" on by default 30 * @requires !(vm.gc == "Shenandoah" & vm.opt.ExplicitGCInvokesConcurrent != false) 31 * @modules java.management 32 * @run main/othervm -Xlog:gc TestFullGCCount 33 */ 34 35 import java.lang.management.GarbageCollectorMXBean; 36 import java.lang.management.ManagementFactory; 37 import java.util.ArrayList; 38 import java.util.HashMap; 39 import java.util.List; 40 41 /* 42 * Originally for a specific failure in CMS, this test now monitors all 43 * collectors for double-counting of collections. 44 */ 45 public class TestFullGCCount { 46 47 static List<GarbageCollectorMXBean> collectors = ManagementFactory.getGarbageCollectorMXBeans(); 48 49 public static void main(String[] args) { 50 int iterations = 20; 51 boolean failed = false; 52 String errorMessage = ""; 53 HashMap<String, List> counts = new HashMap<>(); 54 55 // Prime the collection of count lists for all collectors. 56 for (int i = 0; i < collectors.size(); i++) { 57 GarbageCollectorMXBean collector = collectors.get(i); 58 counts.put(collector.getName(), new ArrayList<>(iterations)); 59 } 60 61 // Perform some gc, record collector counts. 62 for (int i = 0; i < iterations; i++) { 63 System.gc(); 64 addCollectionCount(counts, i); 65 } 66 67 // Check the increments: 68 // Old gen collectors should increase by one, 69 // New collectors may or may not increase. 70 // Any increase >=2 is unexpected. 71 for (String collector : counts.keySet()) { 72 System.out.println("Checking: " + collector); 73 74 for (int i = 0; i < iterations - 1; i++) { 75 List<Long> theseCounts = counts.get(collector); 76 long a = theseCounts.get(i); 77 long b = theseCounts.get(i + 1); 78 if (b - a >= 2) { 79 failed = true; 80 errorMessage += "Collector '" + collector + "' has increment " + (b - a) + 81 " at iteration " + i + "\n"; 82 } 83 } 84 } 85 if (failed) { 86 System.err.println(errorMessage); 87 throw new RuntimeException("FAILED: System.gc collections miscounted."); 88 } 89 System.out.println("Passed."); 90 } 91 92 private static void addCollectionCount(HashMap<String, List> counts, int iteration) { 93 for (int i = 0; i < collectors.size(); i++) { 94 GarbageCollectorMXBean collector = collectors.get(i); 95 List thisList = counts.get(collector.getName()); 96 thisList.add(collector.getCollectionCount()); 97 } 98 } 99 }