1/* 2 * Copyright (c) 2003, 2017, 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 * 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 */ 65import javax.management.*; 66 67public 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 81 /* This listener registers or unregisters the MBean called on2 82 when triggered. */ 83 private static class XListener implements NotificationListener { 84 private boolean firstTime = true; 85 private final boolean register; 86 87 XListener(boolean register) { 88 this.register = register; 89 } 90 91 public void handleNotification(Notification not, Object handback) { 92 if (firstTime) { 93 firstTime = false; 94 Thread t = new Thread() { 95 public void run() { 96 try { 97 if (register) { 98 mbs.createMBean("javax.management.timer.Timer", 99 on2); 100 System.out.println("Listener created " + on2); 101 } else { 102 mbs.unregisterMBean(on2); 103 System.out.println("Listener removed " + on2); 104 } 105 } catch (Exception e) { 106 e.printStackTrace(); 107 } 108 } 109 }; 110 t.start(); 111 try { 112 t.join(); 113 } catch (InterruptedException e) { 114 e.printStackTrace(); // should not happen 115 } 116 } 117 } 118 } 119 120 public static void main(String[] args) throws Exception { 121 122 System.out.println("Test 1: in register notif, unregister an MBean"); 123 mbs = MBeanServerFactory.createMBeanServer(); 124 mbs.createMBean("javax.management.timer.Timer", on2); 125 mbs.addNotificationListener(delName, new XListener(false), null, null); 126 mbs.createMBean("javax.management.timer.Timer", on1); 127 MBeanServerFactory.releaseMBeanServer(mbs); 128 System.out.println("Test 1 completed"); 129 130 System.out.println("Test 2: in unregister notif, unregister an MBean"); 131 mbs = MBeanServerFactory.createMBeanServer(); 132 mbs.createMBean("javax.management.timer.Timer", on1); 133 mbs.createMBean("javax.management.timer.Timer", on2); 134 mbs.addNotificationListener(delName, new XListener(false), null, null); 135 mbs.unregisterMBean(on1); 136 MBeanServerFactory.releaseMBeanServer(mbs); 137 System.out.println("Test 2 completed"); 138 139 System.out.println("Test 3: in register notif, register an MBean"); 140 mbs = MBeanServerFactory.createMBeanServer(); 141 mbs.addNotificationListener(delName, new XListener(true), null, null); 142 mbs.createMBean("javax.management.timer.Timer", on1); 143 MBeanServerFactory.releaseMBeanServer(mbs); 144 System.out.println("Test 3 completed"); 145 146 System.out.println("Test 4: in unregister notif, register an MBean"); 147 mbs = MBeanServerFactory.createMBeanServer(); 148 mbs.createMBean("javax.management.timer.Timer", on1); 149 mbs.addNotificationListener(delName, new XListener(true), null, null); 150 mbs.unregisterMBean(on1); 151 MBeanServerFactory.releaseMBeanServer(mbs); 152 System.out.println("Test 4 completed"); 153 154 System.out.println("Test passed"); 155 } 156} 157