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Java example source code file (ConnectorStopDeadlockTest.java)

This example Java source code file (ConnectorStopDeadlockTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

connectorstopdeadlocktest, exchanger, ioexception, jmxserviceurl, management, mbeanserver, override, rmiconnection, rmiconnectorserver, rmijrmpserverimplsub, string, thread, threadinfo, threading, threadmxbean, threads

The ConnectorStopDeadlockTest.java Java example source code

/*
 * Copyright (c) 2006, 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 6475157
 * @summary Tests deadlock in simultaneous connection and connector-server close
 * @author Eamonn McManus
 */

/* This test is somewhat dependent on implementation details.  If it suddenly
 * starts failing after a rewrite of the RMIConnectorServer code, you should
 * consider whether it is still relevant.
 */

import java.io.IOException;
import java.lang.management.ManagementFactory;
import java.lang.management.ThreadInfo;
import java.lang.management.ThreadMXBean;
import java.util.concurrent.Exchanger;
import javax.management.MBeanServer;
import javax.management.remote.JMXServiceURL;
import javax.management.remote.rmi.RMIConnection;
import javax.management.remote.rmi.RMIConnectorServer;
import javax.management.remote.rmi.RMIJRMPServerImpl;

public class ConnectorStopDeadlockTest {
    private static String failure;
    private static RMIConnectorServer connectorServer;

    public static void main(String[] args) throws Exception {
        JMXServiceURL url = new JMXServiceURL("service:jmx:rmi://");
        MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
        RMIJRMPServerImplSub impl = new RMIJRMPServerImplSub();

        System.out.println("Creating connectorServer");
        connectorServer = new RMIConnectorServer(url, null, impl, mbs);
        System.out.println("Starting connectorServer");
        connectorServer.start();
        System.out.println("Making client");
        RMIConnection cc = impl.newClient(null);
        System.out.println("Closing client");
        cc.close();
        if (connectorServer.isActive()) {
            System.out.println("Stopping connectorServer");
            connectorServer.stop();
        }
        if (failure == null)
            System.out.println("TEST PASSED, no deadlock");
        else
            System.out.println("TEST FAILED");
    }

    static void fail(Throwable e) {
        System.out.println("FAILED WITH EXCEPTION: " + e);
        e.printStackTrace(System.out);
        failure = e.toString();
    }

    static void fail(String s) {
        System.out.println("FAILED: " + s);
        failure = s;
    }

//    static MonitorInfo[] threadLocks(Thread t) {
//        ThreadMXBean tm = ManagementFactory.getThreadMXBean();
//        ThreadInfo[] tis = tm.getThreadInfo(new long[] {t.getId()}, true, true);
//        if (tis[0] == null)
//            return null;
//        else
//            return tis[0].getLockedMonitors();
//    }
//
//    static void showLocks(Thread t) {
//        System.out.println("Locks for " + t.getName() + ":");
//        MonitorInfo[] mis = threadLocks(t);
//        if (mis == null)
//            System.out.println("  (no longer exists)");
//        else if (mis.length == 0)
//            System.out.println("  (none)");
//        else {
//            for (MonitorInfo mi : mis)
//                System.out.println("  " + mi);
//        }
//    }

    // Wait until thread t blocks waiting for a lock held by the calling thread,
    // or until it exits.
    static void waitForBlock(Thread t) {
        Thread currentThread = Thread.currentThread();
        System.out.println("waiting for thread " + t.getName() + " to block " +
                "on a lock held by thread " + currentThread.getName());
        ThreadMXBean tm = ManagementFactory.getThreadMXBean();
        while (true) {
            ThreadInfo ti = tm.getThreadInfo(t.getId());
            if (ti == null) {
                System.out.println("  thread has exited");
                return;
            }
            if (ti.getLockOwnerId() == currentThread.getId()) {
                System.out.println("  thread now blocked");
                return;
            }
            Thread.yield();
        }
    }

    public static class RMIJRMPServerImplSub extends RMIJRMPServerImpl {
        RMIJRMPServerImplSub() throws IOException {
            super(0, null, null, null);
        }

        public RMIConnection makeClient() throws IOException {
            return super.makeClient("connection id", null);
        }

        @Override
        protected void clientClosed(RMIConnection conn) throws IOException {
            System.out.println("clientClosed, will call connectorServer.stop");
            final Exchanger<Void> x = new Exchanger();
            Thread t = new Thread() {
                public void run() {
                    try {
                        connectorServer.stop();
                    } catch (Exception e) {
                        fail(e);
                    }
                }
            };
            t.setName("connectorServer.stop");
            t.start();
            waitForBlock(t);
            /* If this thread is synchronized on RMIServerImpl, then
             * the thread that does connectorServer.stop will acquire
             * the clientList lock and then block waiting for the RMIServerImpl
             * lock.  Our call to super.clientClosed will then deadlock because
             * it needs to acquire the clientList lock.
             */
            System.out.println("calling super.clientClosed");
            System.out.flush();
            super.clientClosed(conn);
        }
    }
}

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