1 /* 2 * Copyright (c) 2006, 2020, 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 26 * @bug 4994705 27 * 28 * @summary deadlock in LogManager 29 * @author Serguei Spitsyn / SAP 30 * 31 * @library /test/lib 32 * @build LoggingDeadlock 33 * @run main/timeout=15 LoggingDeadlock 34 * @key randomness 35 */ 36 37 /* 38 * 39 * There can be a deadlock between two class initializations. 40 * It happens if the LogManager.<clinit> and the Logger.<clinit> 41 * are invoked concurrently on two different threads. 42 * There is a cyclic dependence between the two static initializers: 43 * 1. LogManager.<clinit> instantiate the class RootLogger which 44 * is a subclass of the Logger class. 45 * It requires the Logger class initialization to complete. 46 * 2. Logger.<clinit> initializes the field "global", so it 47 * it makes a call: Logger.getLogger("global"). 48 * Subsequently the LogManager static method getLogManager() 49 * is called which requires the LogManager class 50 * initialization to complete. 51 * This cyclic dependence causes a deadlock, so two class 52 * initializations are waiting for each other. 53 * This is a regression test for this bug. 54 */ 55 56 57 import java.util.Random; 58 import java.util.logging.LogManager; 59 import java.util.logging.Logger; 60 import jdk.test.lib.RandomFactory; 61 62 public class LoggingDeadlock { 63 64 private static int preventLoopElision; 65 private static final Random random = RandomFactory.getRandom(); 66 randomDelay()67 public static void randomDelay() { 68 int runs = random.nextInt(1000000); 69 int c = 0; 70 71 for (int i = 0; i < runs; ++i) { 72 c = c + i; 73 } 74 preventLoopElision = c; 75 } 76 main(String[] args)77 public static void main(String[] args) throws InterruptedException{ 78 Thread t1 = new Thread(new Runnable() { 79 public void run() { 80 randomDelay(); 81 // Trigger Logger.<clinit> 82 Logger.getAnonymousLogger(); 83 } 84 }); 85 86 Thread t2 = new Thread(new Runnable() { 87 public void run() { 88 randomDelay(); 89 // Trigger LogManager.<clinit> 90 LogManager.getLogManager(); 91 } 92 }); 93 94 t1.start(); 95 t2.start(); 96 97 t1.join(); 98 t2.join(); 99 System.out.println("\nTest passed"); 100 } 101 } 102