1 /*
   2  * Copyright (c) 1999, 2013 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
  21  * questions.
  22  */
  23 
  24 /**
  25  * @test
  26  * @bug 4176355 7181748
  27  * @summary Suspending a ThreadGroup that contains the current thread has
  28  *          unpredictable results.
  29  */
  30 
  31 public class Suspend implements Runnable {
  32 
  33     private static int count = 0;
  34     private static final ThreadGroup group = new ThreadGroup("");
  35     private static final Thread first = new Thread(group, new Suspend());
  36     private static final Thread second = new Thread(group, new Suspend());
  37 
  38     public void run() {
  39         while (true) {
  40             try {
  41                 Thread.sleep(100);
  42                 if (Thread.currentThread() == first) {
  43                     if (second.isAlive()) {
  44                         group.suspend();
  45                     }
  46                 } else {
  47                     count++;
  48                 }
  49             } catch (InterruptedException e) {
  50             }
  51         }
  52     }
  53 
  54     public static void main(String[] args) throws Exception {
  55         // Launch two threads as part of the same thread group
  56         first.start();
  57         second.start();
  58 
  59         // Wait for the thread group suspend to be issued
  60         while (!first.isAlive() || !second.isAlive()) {
  61             Thread.sleep(100);
  62         }
  63         Thread.sleep(1000);
  64         // Suppose, the thread group is now suspended
  65 
  66         count = 0;
  67         Thread.sleep(1000);
  68 
  69         // Increment of the count indicates that the second thread is still running
  70         boolean failed = (count > 1);
  71         first.stop();
  72         second.stop();
  73         if (failed)
  74             throw new RuntimeException("Failure.");
  75     }
  76 }