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
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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 volatile 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     }
77 }