1 /*
   2  * Copyright (c) 2003, 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
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  22  */
  23 
  24 /*
  25  * @test
  26  * @bug     4892507
  27  * @summary Basic Test for the following reset methods:
  28  *          - ThreadMXBean.findMonitorDeadlockedThreads()
  29  * @author  Mandy Chung
  30  *
  31  * @modules java.management
  32  * @build MonitorDeadlock
  33  * @build ThreadDump
  34  * @run main/othervm FindMonitorDeadlock
  35  */
  36 
  37 import java.lang.management.*;
  38 import java.util.*;
  39 
  40 public class FindMonitorDeadlock {
  41     public static void main(String[] argv) {
  42         // create deadlocked threads
  43         MonitorDeadlock md = new MonitorDeadlock();
  44 
  45         // No deadlock
  46         ThreadMXBean mbean = ManagementFactory.getThreadMXBean();
  47         long[] threads = mbean.findMonitorDeadlockedThreads();
  48         if (threads != null) {
  49             throw new RuntimeException("TEST FAILED: Should return null.");
  50         }
  51 
  52         // Let the threads to proceed
  53         md.goDeadlock();
  54 
  55         // wait until the deadlock is ready
  56         md.waitUntilDeadlock();
  57 
  58         // Find Deadlock
  59         threads = mbean.findMonitorDeadlockedThreads();
  60         if (threads == null) {
  61             ThreadDump.dumpStacks();
  62             throw new RuntimeException("TEST FAILED: Deadlock not detected.");
  63         }
  64 
  65         // Print Deadlock stack trace
  66         System.out.println("Found threads that are in deadlock:-");
  67         ThreadInfo[] infos = mbean.getThreadInfo(threads, Integer.MAX_VALUE);
  68         for (int i = 0; i < infos.length; i++) {
  69             ThreadDump.printThreadInfo(infos[i]);
  70         }
  71 
  72         md.checkResult(threads);
  73         System.out.println("Test passed");
  74     }
  75 }