1 /* 2 * Copyright (c) 2005, 2015, 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 6331746 27 * @summary Test a deadlock and will be blocked forever if the deadlock is present. 28 * @author Shanliang JIANG 29 * @modules java.management 30 * @run main DeadlockTest 31 */ 32 33 import javax.management.*; 34 import javax.management.timer.*; 35 36 public class DeadlockTest extends StandardMBean { 37 public <T> DeadlockTest(T implementation, Class<T> mbeanInterface) 38 throws NotCompliantMBeanException { 39 super(implementation, mbeanInterface); 40 } 41 42 public MBeanInfo getCachedMBeanInfo() { 43 return super.getCachedMBeanInfo(); 44 } 45 46 public void cacheMBeanInfo(MBeanInfo mi) { 47 super.cacheMBeanInfo(mi); 48 } 49 50 public static void main(String[] args) throws Exception { 51 System.out.println("main: No deadlock please."); 52 53 System.out.println("main: Create a BadBay to hold the lock forever."); 54 DeadlockTest dt = new DeadlockTest(new Timer(), TimerMBean.class); 55 56 BadBoy bb = new BadBoy(dt); 57 bb.start(); 58 59 synchronized(bb) { 60 while(!bb.gotLock) { 61 bb.wait(); // if blocked here, means failing to get lock, impossible. 62 } 63 } 64 65 System.out.println("main: The BadBay is holding the lock forever."); 66 67 System.out.println("main: Create a WorkingBoy to see blocking ..."); 68 WorkingBoy wb = new WorkingBoy(dt); 69 70 synchronized(wb) { 71 wb.start(); 72 73 while(!wb.done) { 74 wb.wait(); // if blocked here, the deadlock happends 75 } 76 } 77 78 System.out.println("main: OK, bye bye."); 79 } 80 81 private static class BadBoy extends Thread { 82 public BadBoy(Object o) { 83 setDaemon(true); 84 85 this.o = o; 86 } 87 88 public void run() { 89 System.out.println("BadBoy-run: keep synchronization lock forever!"); 90 91 synchronized(o) { 92 synchronized(this) { 93 gotLock = true; 94 95 this.notify(); 96 } 97 98 try { 99 Thread.sleep(10000000); 100 } catch (Exception e) { 101 // OK 102 } 103 } 104 } 105 106 final Object o; 107 public boolean gotLock; 108 } 109 110 private static class WorkingBoy extends Thread { 111 public WorkingBoy(DeadlockTest sm) { 112 setDaemon(true); 113 114 this.sm = sm; 115 } 116 117 public void run() { 118 try { 119 System.out.println("WorkingBoy-run: calling StandardMBean methods ..."); 120 121 System.out.println("WorkingBoy-run: calling setImplementation ..."); 122 sm.setImplementation(new Timer()); 123 124 System.out.println("WorkingBoy-run: calling getImplementation ..."); 125 sm.getImplementation(); 126 127 System.out.println("WorkingBoy-run: calling getMBeanInterface ..."); 128 sm.getMBeanInterface(); 129 130 System.out.println("WorkingBoy-run: calling getImplementationClass ..."); 131 sm.getImplementationClass(); 132 133 System.out.println("WorkingBoy-run: calling cacheMBeanInfo ..."); 134 sm.cacheMBeanInfo(null); 135 136 System.out.println("WorkingBoy-run: calling getCachedMBeanInfo ..."); 137 sm.getCachedMBeanInfo(); 138 139 System.out.println("WorkingBoy-run: All done!"); 140 141 synchronized(this) { 142 done = true; 143 144 this.notifyAll(); 145 } 146 } catch (NotCompliantMBeanException ne) { 147 // Impossible? 148 throw new RuntimeException(ne); 149 } 150 } 151 152 final DeadlockTest sm; 153 public boolean done; 154 } 155 }