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 6318664 27 * @summary Test deadlock in MBeanRegistration.preDeregister method 28 * @author Eamonn McManus 29 * 30 * @run clean PreDeregisterDeadlockTest 31 * @run build PreDeregisterDeadlockTest 32 * @run main PreDeregisterDeadlockTest 33 */ 34 35import java.util.concurrent.*; 36import javax.management.*; 37 38public class PreDeregisterDeadlockTest { 39 public static interface BlibbyMBean {} 40 41 public static class Blibby implements BlibbyMBean, MBeanRegistration { 42 public Blibby(MBeanServer mbs, ObjectName otherName) { 43 this.mbs = mbs; 44 this.otherName = otherName; 45 } 46 47 public ObjectName preRegister(MBeanServer mbs, ObjectName on) { 48 return on; 49 } 50 51 public void postRegister(Boolean done) {} 52 53 public void preDeregister() { 54 if (otherName == null) 55 return; 56 try { 57 Thread t = new Thread() { 58 public void run() { 59 try { 60 mbs.unregisterMBean(otherName); 61 } catch (Throwable e) { 62 e.printStackTrace(System.out); 63 fail(e.toString()); 64 } 65 } 66 }; 67 t.start(); 68 t.join(5000L); 69 if (t.isAlive()) 70 fail("Deadlock detected"); 71 } catch (Throwable e) { 72 e.printStackTrace(System.out); 73 fail(e.toString()); 74 } 75 } 76 77 public void postDeregister() {} 78 79 private final MBeanServer mbs; 80 private final ObjectName otherName; 81 } 82 83 public static interface BlobbyMBean {} 84 85 public static class Blobby implements BlobbyMBean, MBeanRegistration { 86 public Blobby(MBeanServer mbs, Semaphore semaphore) { 87 this.mbs = mbs; 88 this.semaphore = semaphore; 89 } 90 91 public ObjectName preRegister(MBeanServer mbs, ObjectName on) { 92 this.objectName = on; 93 return on; 94 } 95 96 public void postRegister(Boolean done) {} 97 98 public void preDeregister() throws Exception { 99 Thread t = new Thread() { 100 public void run() { 101 try { 102 mbs.unregisterMBean(objectName); 103 fail("Nested unregister succeeded"); 104 } catch (InstanceNotFoundException e) { 105 semaphore.release(); 106 } catch (Throwable e) { 107 e.printStackTrace(System.out); 108 fail(e.toString()); 109 } 110 } 111 }; 112 t.start(); 113 // Give the thread a chance to block so we are really 114 // testing parallelism. (On slow machines we might not 115 // really be testing it but we should be covered by our 116 // faster machines.) 117 Thread.sleep(500L); 118 } 119 120 public void postDeregister() {} 121 122 private final MBeanServer mbs; 123 private ObjectName objectName; 124 private final Semaphore semaphore; 125 } 126 127 public static void main(String[] args) throws Exception { 128 MBeanServer mbs = MBeanServerFactory.newMBeanServer(); 129 ObjectName on1 = new ObjectName("a:type=Blibby,name=\"1\""); 130 ObjectName on2 = new ObjectName("a:type=Blibby,name=\"2\""); 131 132 // Test 1: preDeregister starts a thread which unregisters a 133 // different MBean: this must not deadlock 134 mbs.registerMBean(new Blibby(mbs, on2), on1); 135 mbs.registerMBean(new Blibby(mbs, null), on2); 136 mbs.unregisterMBean(on1); 137 138 // Test 2: preDeregister starts a thread which tries to 139 // unregister the same MBean: this thread should block until 140 // the original thread succeeds in unregistering, then 141 // get an InstanceNotFoundException. We wait for it to 142 // complete here, using the semaphore. 143 Semaphore semaphore = new Semaphore(0); 144 mbs.registerMBean(new Blobby(mbs, semaphore), on1); 145 mbs.unregisterMBean(on1); 146 boolean ok = semaphore.tryAcquire(1, 5, TimeUnit.SECONDS); 147 if (!ok) 148 fail("Second unregister thread did not complete"); 149 150 if (failure == null) 151 System.out.println("OK: Test passed"); 152 else 153 throw new Exception("TEST FAILED: " + failure); 154 } 155 156 private static void fail(String why) { 157 System.out.println("FAILED: " + why); 158 failure = why; 159 } 160 161 private static volatile String failure; 162} 163