/*

 * Copyright (c) 2013, 2016, 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.

 */

import jdk.test.lib.Utils;

import java.lang.management.ManagementFactory;

import java.lang.management.ThreadMXBean;

import java.util.Random;

/*

 * @test

 * @bug 8016304

 * @summary Make sure no deadlock is reported for this program which has no deadlocks.

 * @modules java.base/jdk.internal.misc

 * @library /test/lib

 * @run main/othervm TestFalseDeadLock

 */

/*

 * This test will not provoke the bug every time it is run since the bug is intermittent.

 * The test has a fixed running time of 5 seconds.

 */

public class TestFalseDeadLock {

    private static ThreadMXBean bean;

    private static volatile boolean running = true;

    private static volatile boolean found = false;

    public static void main(String[] args) throws Exception {

        bean = ManagementFactory.getThreadMXBean();

        Thread[] threads = new Thread[500];

        for (int i = 0; i < threads.length; i++) {

            Test t = new Test();

            threads[i] = new Thread(t);

            threads[i].start();

        }

        try {

            Thread.sleep(5000);

        } catch (InterruptedException ex) {

        }

        running = false;

        for (Thread t : threads) {

            t.join();

        }

        if (found) {

            throw new Exception("Deadlock reported, but there is no deadlock.");

        }

    }

    public static class Test implements Runnable {

        public void run() {

            Random r = Utils.getRandomInstance();

            while (running) {

                try {

                    synchronized (this) {

                        wait(r.nextInt(1000) + 1);

                    }

                } catch (InterruptedException ex) {

                }

                recurse(2000);

            }

            if (bean.findDeadlockedThreads() != null) {

                System.out.println("FOUND!");

                found = true;

            }

        }

        private void recurse(int i) {

            if (!running) {

                // It is important for the test to call println here

                // since there are locks inside that path.

                System.out.println("Hullo");

            }

            else if (i > 0) {

                recurse(i - 1);

            }

        }

    }

}