1 /*
   2  * Copyright (c) 2005, 2014, 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.
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  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  * @run main DeadlockTest
  30  */
  31 
  32 import javax.management.*;
  33 import javax.management.timer.*;
  34 
  35 public class DeadlockTest extends StandardMBean {
  36     public <T> DeadlockTest(T implementation, Class<T> mbeanInterface)
  37     throws NotCompliantMBeanException {
  38         super(implementation, mbeanInterface);
  39     }
  40 
  41     public MBeanInfo getCachedMBeanInfo() {
  42         return super.getCachedMBeanInfo();
  43     }
  44 
  45     public void cacheMBeanInfo(MBeanInfo mi) {
  46         super.cacheMBeanInfo(mi);
  47     }
  48 
  49     public static void main(String[] args) throws Exception {
  50         System.out.println("main: No deadlock please.");
  51 
  52         System.out.println("main: Create a BadBay to hold the lock forever.");
  53         DeadlockTest dt = new DeadlockTest(new Timer(), TimerMBean.class);
  54 
  55         BadBoy bb = new BadBoy(dt);
  56         bb.start();
  57 
  58         synchronized(bb) {
  59             while(!bb.gotLock) {
  60                 bb.wait(); // if blocked here, means failing to get lock, impossible.
  61             }
  62         }
  63 
  64         System.out.println("main: The BadBay is holding the lock forever.");
  65 
  66         System.out.println("main: Create a WorkingBoy to see blocking ...");
  67         WorkingBoy wb = new WorkingBoy(dt);
  68 
  69         synchronized(wb) {
  70             wb.start();
  71 
  72             while(!wb.done) {
  73                 wb.wait(); // if blocked here, the deadlock happends
  74             }
  75         }
  76 
  77         System.out.println("main: OK, bye bye.");
  78     }
  79 
  80     private static class BadBoy extends Thread {
  81         public BadBoy(Object o) {
  82             setDaemon(true);
  83 
  84             this.o = o;
  85         }
  86 
  87         public void run() {
  88             System.out.println("BadBoy-run: keep synchronization lock forever!");
  89 
  90             synchronized(o) {
  91                 synchronized(this) {
  92                     gotLock = true;
  93 
  94                     this.notify();
  95                 }
  96 
  97                 try {
  98                     Thread.sleep(10000000);
  99                 } catch (Exception e) {
 100                     // OK
 101                 }
 102             }
 103         }
 104 
 105         final Object o;
 106         public boolean gotLock;
 107     }
 108 
 109     private static class WorkingBoy extends Thread {
 110         public WorkingBoy(DeadlockTest sm) {
 111             setDaemon(true);
 112 
 113             this.sm = sm;
 114         }
 115 
 116         public void run() {
 117             try {
 118                 System.out.println("WorkingBoy-run: calling StandardMBean methods ...");
 119 
 120                 System.out.println("WorkingBoy-run: calling setImplementation ...");
 121                 sm.setImplementation(new Timer());
 122 
 123                 System.out.println("WorkingBoy-run: calling getImplementation ...");
 124                 sm.getImplementation();
 125 
 126                 System.out.println("WorkingBoy-run: calling getMBeanInterface ...");
 127                 sm.getMBeanInterface();
 128 
 129                 System.out.println("WorkingBoy-run: calling getImplementationClass ...");
 130                 sm.getImplementationClass();
 131 
 132                 System.out.println("WorkingBoy-run: calling cacheMBeanInfo ...");
 133                 sm.cacheMBeanInfo(null);
 134 
 135                 System.out.println("WorkingBoy-run: calling getCachedMBeanInfo ...");
 136                 sm.getCachedMBeanInfo();
 137 
 138                 System.out.println("WorkingBoy-run: All done!");
 139 
 140                 synchronized(this) {
 141                     done = true;
 142 
 143                     this.notifyAll();
 144                 }
 145             } catch (NotCompliantMBeanException ne) {
 146                 // Impossible?
 147                 throw new RuntimeException(ne);
 148             }
 149         }
 150 
 151         final DeadlockTest sm;
 152         public boolean done;
 153     }
 154 }