| /* |
| * Copyright (c) 2003, 2017, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| /* |
| * @test |
| * @bug 4757273 |
| * @summary Test deadlock in MBeanServerDelegate listeners |
| * @author Eamonn McManus |
| * |
| * @run clean NotifDeadlockTest |
| * @run build NotifDeadlockTest |
| * @run main NotifDeadlockTest |
| */ |
| |
| /* |
| * Test deadlock when a listener for an MBeanServerDelegate does a |
| * register or unregister of an MBean. Since such a listener is |
| * triggered by a register or unregister operation, deadlock scenarios |
| * are possible if there are any locks held while the listener is |
| * being dispatched. |
| * |
| * The flow of control looks rather like this: |
| * |
| * Thread 1: |
| * - MBeanServer.createMBean(..., objectName1); |
| * --- MBeanServerDelegate.sendNotification |
| * ----- XListener.handleNotification |
| * ------- create Thread 2 |
| * ------- wait for Thread 2 to complete |
| * |
| * Thread 2: |
| * - MBeanServer.createMBean(..., objectName2); |
| * - end Thread 2 |
| * |
| * If any locks are held by Thread 1 within createMBean or |
| * sendNotification, then Thread 2 can block waiting for them. |
| * Since Thread 1 is itself waiting for Thread 2, this is a deadlock. |
| * |
| * We test all four combinations of: |
| * (Thread1-create,Thread1-unregister) x (Thread2-create,Thread2-unregister) |
| * |
| * In the JMX 1.1 RI, all four tests fail. In the JMX 1.2 RI, all four |
| * tests should pass. |
| */ |
| import javax.management.*; |
| |
| public class NotifDeadlockTest { |
| static ObjectName on1, on2, delName; |
| static { |
| try { |
| on1 = new ObjectName("thing:a=b"); |
| on2 = new ObjectName("thing:c=d"); |
| delName = |
| new ObjectName("JMImplementation:type=MBeanServerDelegate"); |
| } catch (MalformedObjectNameException e) { |
| throw new Error(); |
| } |
| } |
| static MBeanServer mbs; |
| |
| /* This listener registers or unregisters the MBean called on2 |
| when triggered. */ |
| private static class XListener implements NotificationListener { |
| private boolean firstTime = true; |
| private final boolean register; |
| |
| XListener(boolean register) { |
| this.register = register; |
| } |
| |
| public void handleNotification(Notification not, Object handback) { |
| if (firstTime) { |
| firstTime = false; |
| Thread t = new Thread() { |
| public void run() { |
| try { |
| if (register) { |
| mbs.createMBean("javax.management.timer.Timer", |
| on2); |
| System.out.println("Listener created " + on2); |
| } else { |
| mbs.unregisterMBean(on2); |
| System.out.println("Listener removed " + on2); |
| } |
| } catch (Exception e) { |
| e.printStackTrace(); |
| } |
| } |
| }; |
| t.start(); |
| try { |
| t.join(); |
| } catch (InterruptedException e) { |
| e.printStackTrace(); // should not happen |
| } |
| } |
| } |
| } |
| |
| public static void main(String[] args) throws Exception { |
| |
| System.out.println("Test 1: in register notif, unregister an MBean"); |
| mbs = MBeanServerFactory.createMBeanServer(); |
| mbs.createMBean("javax.management.timer.Timer", on2); |
| mbs.addNotificationListener(delName, new XListener(false), null, null); |
| mbs.createMBean("javax.management.timer.Timer", on1); |
| MBeanServerFactory.releaseMBeanServer(mbs); |
| System.out.println("Test 1 completed"); |
| |
| System.out.println("Test 2: in unregister notif, unregister an MBean"); |
| mbs = MBeanServerFactory.createMBeanServer(); |
| mbs.createMBean("javax.management.timer.Timer", on1); |
| mbs.createMBean("javax.management.timer.Timer", on2); |
| mbs.addNotificationListener(delName, new XListener(false), null, null); |
| mbs.unregisterMBean(on1); |
| MBeanServerFactory.releaseMBeanServer(mbs); |
| System.out.println("Test 2 completed"); |
| |
| System.out.println("Test 3: in register notif, register an MBean"); |
| mbs = MBeanServerFactory.createMBeanServer(); |
| mbs.addNotificationListener(delName, new XListener(true), null, null); |
| mbs.createMBean("javax.management.timer.Timer", on1); |
| MBeanServerFactory.releaseMBeanServer(mbs); |
| System.out.println("Test 3 completed"); |
| |
| System.out.println("Test 4: in unregister notif, register an MBean"); |
| mbs = MBeanServerFactory.createMBeanServer(); |
| mbs.createMBean("javax.management.timer.Timer", on1); |
| mbs.addNotificationListener(delName, new XListener(true), null, null); |
| mbs.unregisterMBean(on1); |
| MBeanServerFactory.releaseMBeanServer(mbs); |
| System.out.println("Test 4 completed"); |
| |
| System.out.println("Test passed"); |
| } |
| } |