1 /* 2 * Copyright (c) 2003, 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 4757273 27 * @summary Test deadlock in MBeanServerDelegate listeners 28 * @author Eamonn McManus 29 * @modules java.management 30 * @run clean NotifDeadlockTest 31 * @run build NotifDeadlockTest 32 * @run main NotifDeadlockTest 33 */ 34 35 /* 36 * Test deadlock when a listener for an MBeanServerDelegate does a 37 * register or unregister of an MBean. Since such a listener is 38 * triggered by a register or unregister operation, deadlock scenarios 39 * are possible if there are any locks held while the listener is 40 * being dispatched. 41 * 42 * The flow of control looks rather like this: 43 * 44 * Thread 1: 45 * - MBeanServer.createMBean(..., objectName1); 46 * --- MBeanServerDelegate.sendNotification 47 * ----- XListener.handleNotification 48 * ------- create Thread 2 49 * ------- wait for Thread 2 to complete 50 * 51 * Thread 2: 52 * - MBeanServer.createMBean(..., objectName2); 53 * - end Thread 2 54 * 55 * If any locks are held by Thread 1 within createMBean or 56 * sendNotification, then Thread 2 can block waiting for them. 57 * Since Thread 1 is itself waiting for Thread 2, this is a deadlock. 58 * 59 * We test all four combinations of: 60 * (Thread1-create,Thread1-unregister) x (Thread2-create,Thread2-unregister) 61 * 62 * In the JMX 1.1 RI, all four tests fail. In the JMX 1.2 RI, all four 63 * tests should pass. 64 */ 65 import javax.management.*; 66 67 public class NotifDeadlockTest { 68 static ObjectName on1, on2, delName; 69 static { 70 try { 71 on1 = new ObjectName("thing:a=b"); 72 on2 = new ObjectName("thing:c=d"); 73 delName = 74 new ObjectName("JMImplementation:type=MBeanServerDelegate"); 75 } catch (MalformedObjectNameException e) { 76 throw new Error(); 77 } 78 } 79 static MBeanServer mbs; 80 static boolean timedOut; 81 82 /* This listener registers or unregisters the MBean called on2 83 when triggered. */ 84 private static class XListener implements NotificationListener { 85 private boolean firstTime = true; 86 private final boolean register; 87 88 XListener(boolean register) { 89 this.register = register; 90 } 91 92 public void handleNotification(Notification not, Object handback) { 93 if (firstTime) { 94 firstTime = false; 95 Thread t = new Thread() { 96 public void run() { 97 try { 98 if (register) { 99 mbs.createMBean("javax.management.timer.Timer", 100 on2); 101 System.out.println("Listener created " + on2); 102 } else { 103 mbs.unregisterMBean(on2); 104 System.out.println("Listener removed " + on2); 105 } 106 } catch (Exception e) { 107 e.printStackTrace(); 108 } 109 } 110 }; 111 t.start(); 112 try { 113 t.join(2000); 114 } catch (InterruptedException e) { 115 e.printStackTrace(); // should not happen 116 } 117 if (t.isAlive()) { 118 System.out.println("FAILURE: Wait timed out: " + 119 "probable deadlock"); 120 timedOut = true; 121 } 122 } 123 } 124 } 125 126 public static void main(String[] args) throws Exception { 127 boolean success = true; 128 129 System.out.println("Test 1: in register notif, unregister an MBean"); 130 timedOut = false; 131 mbs = MBeanServerFactory.createMBeanServer(); 132 mbs.createMBean("javax.management.timer.Timer", on2); 133 mbs.addNotificationListener(delName, new XListener(false), null, null); 134 mbs.createMBean("javax.management.timer.Timer", on1); 135 MBeanServerFactory.releaseMBeanServer(mbs); 136 if (timedOut) { 137 success = false; 138 Thread.sleep(500); 139 // wait for the spawned thread to complete its work, probably 140 } 141 System.out.println("Test 1 completed"); 142 143 System.out.println("Test 2: in unregister notif, unregister an MBean"); 144 timedOut = false; 145 mbs = MBeanServerFactory.createMBeanServer(); 146 mbs.createMBean("javax.management.timer.Timer", on1); 147 mbs.createMBean("javax.management.timer.Timer", on2); 148 mbs.addNotificationListener(delName, new XListener(false), null, null); 149 mbs.unregisterMBean(on1); 150 MBeanServerFactory.releaseMBeanServer(mbs); 151 if (timedOut) { 152 success = false; 153 Thread.sleep(500); 154 // wait for the spawned thread to complete its work, probably 155 } 156 System.out.println("Test 2 completed"); 157 158 System.out.println("Test 3: in register notif, register an MBean"); 159 timedOut = false; 160 mbs = MBeanServerFactory.createMBeanServer(); 161 mbs.addNotificationListener(delName, new XListener(true), null, null); 162 mbs.createMBean("javax.management.timer.Timer", on1); 163 MBeanServerFactory.releaseMBeanServer(mbs); 164 if (timedOut) { 165 success = false; 166 Thread.sleep(500); 167 // wait for the spawned thread to complete its work, probably 168 } 169 System.out.println("Test 3 completed"); 170 171 System.out.println("Test 4: in unregister notif, register an MBean"); 172 timedOut = false; 173 mbs = MBeanServerFactory.createMBeanServer(); 174 mbs.createMBean("javax.management.timer.Timer", on1); 175 mbs.addNotificationListener(delName, new XListener(true), null, null); 176 mbs.unregisterMBean(on1); 177 MBeanServerFactory.releaseMBeanServer(mbs); 178 if (timedOut) { 179 success = false; 180 Thread.sleep(500); 181 // wait for the spawned thread to complete its work, probably 182 } 183 System.out.println("Test 4 completed"); 184 185 if (success) 186 System.out.println("Test passed"); 187 else { 188 System.out.println("TEST FAILED: at least one subcase failed"); 189 System.exit(1); 190 } 191 } 192 }