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 *

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 * 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

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 *

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 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

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/*

 * @test

 * @bug     6337571

 * @summary Test if findDeadlockedThreads works for an ownable synchronizer

 *          in shared mode which has no owner when a thread is parked.

 * @author  Mandy Chung

 *

 * @run main/othervm SharedSynchronizer

 */

import java.util.concurrent.*;

import java.lang.management.ManagementFactory;

import java.lang.management.ThreadMXBean;

public class SharedSynchronizer {

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

        MyThread t = new MyThread();

        t.setDaemon(true);

        t.start();

        ThreadMXBean tmbean = ManagementFactory.getThreadMXBean();

        if (!tmbean.isSynchronizerUsageSupported()) {

            System.out.println("Monitoring of synchronizer usage not supported")

;

            return;

        }

        long[] result = tmbean.findDeadlockedThreads();

        if (result != null) {

             throw new RuntimeException("TEST FAILED: result should be null");

        }

    }

    static class MyThread extends Thread {

        public void run() {

            FutureTask f = new FutureTask(

                new Callable() {

                    public Object call() {

                        throw new RuntimeException("should never reach here");

                    }

                }

            );

            // A FutureTask uses the AbstractOwnableSynchronizer in a shared

            // mode (not exclusive mode). When the thread calls f.get(),

            // it will put to park on the ownable synchronizer that

            // is not owned by any thread.

            try {

                f.get();

            } catch (Exception e) {

                RuntimeException re = new RuntimeException(e.getMessage());

                re.initCause(e);

                throw re;

            }

        }

    }

}