1 /*
2 * Copyright (c) 2003, 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 4530538
27 * @summary Basic unit test of ThreadInfo.getBlockedCount()
28 * @author Alexei Guibadoulline and Mandy Chung
29 * @author Jaroslav Bachorik
30 * @run main ThreadBlockedCount
31 */
32
33 import java.lang.management.*;
34 import java.util.concurrent.Phaser;
35
36 public class ThreadBlockedCount {
37 final static long EXPECTED_BLOCKED_COUNT = 3;
38 final static int DEPTH = 10;
39 private static final ThreadMXBean mbean
40 = ManagementFactory.getThreadMXBean();
41
42 private static final Object a = new Object();
43 private static final Object b = new Object();
44 private static final Object c = new Object();
45
46 private static final Object blockedObj1 = new Object();
47 private static final Object blockedObj2 = new Object();
48 private static final Object blockedObj3 = new Object();
49 private static volatile boolean testOk = true;
50 private static BlockingThread blocking;
51 private static BlockedThread blocked;
52
53 public static void main(String args[]) throws Exception {
54 // real run
55 runTest();
56 if (!testOk) {
57 throw new RuntimeException("TEST FAILED.");
58 }
59 System.out.println("Test passed.");
60 }
61
62 private static void runTest() throws Exception {
63 final Phaser p = new Phaser(2);
64
65 blocking = new BlockingThread(p);
66 blocking.start();
67
68 blocked = new BlockedThread(p);
69 blocked.start();
70
71 try {
72 blocking.join();
73
74 testOk = checkBlocked();
75 p.arriveAndAwaitAdvance(); // #5
76
77 } catch (InterruptedException e) {
78 System.err.println("Unexpected exception.");
79 e.printStackTrace(System.err);
80 throw e;
81 }
82 }
83
84
85 static class BlockedThread extends Thread {
86 private final Phaser p;
87
88 BlockedThread(Phaser p) {
89 super("BlockedThread");
90 this.p = p;
91 }
92
93 public void run() {
94 int accumulator = 0;
95 p.arriveAndAwaitAdvance(); // #1
96
97 // Enter lock a without blocking
98 synchronized (a) {
99 p.arriveAndAwaitAdvance(); // #2
100
101 // Block to enter blockedObj1
102 // blockedObj1 should be owned by BlockingThread
103 synchronized (blockedObj1) {
104 accumulator++; // filler
105 }
106 }
107
108 // Enter lock a without blocking
109 synchronized (b) {
110 // wait until BlockingThread holds blockedObj2
111 p.arriveAndAwaitAdvance(); // #3
112
113 // Block to enter blockedObj2
114 // blockedObj2 should be owned by BlockingThread
115 synchronized (blockedObj2) {
116 accumulator++; // filler
117 }
118 }
119
120 // Enter lock a without blocking
121 synchronized (c) {
122 // wait until BlockingThread holds blockedObj3
123 p.arriveAndAwaitAdvance(); // #4
124
125 // Block to enter blockedObj3
126 // blockedObj3 should be owned by BlockingThread
127 synchronized (blockedObj3) {
128 accumulator++; // filler
129 }
130 }
131
132 // wait for the main thread to check the blocked count
133 System.out.println("Acquired " + accumulator + " monitors");
134 p.arriveAndAwaitAdvance(); // #5
135 // ... and we can leave now
136 } // run()
137 } // BlockedThread
138
139 static class BlockingThread extends Thread {
140 private final Phaser p;
141
142 BlockingThread(Phaser p) {
143 super("BlockingThread");
144 this.p = p;
145 }
146
147 private void waitForBlocked() {
148 // wait for BlockedThread.
149 p.arriveAndAwaitAdvance();
150
151 boolean threadBlocked = false;
152 while (!threadBlocked) {
153 // give a chance for BlockedThread to really block
154 try {
155 Thread.sleep(50);
156 } catch (InterruptedException e) {
157 System.err.println("Unexpected exception.");
158 e.printStackTrace(System.err);
159 testOk = false;
160 break;
161 }
162 ThreadInfo info = mbean.getThreadInfo(blocked.getId());
163 threadBlocked = (info.getThreadState() == Thread.State.BLOCKED);
164 }
165 }
166
167 public void run() {
168 p.arriveAndAwaitAdvance(); // #1
169
170 synchronized (blockedObj1) {
171 System.out.println("BlockingThread attempts to notify a");
172 waitForBlocked(); // #2
173 }
174
175 // block until BlockedThread is ready
176 synchronized (blockedObj2) {
177 System.out.println("BlockingThread attempts to notify b");
178 waitForBlocked(); // #3
179 }
180
181 // block until BlockedThread is ready
182 synchronized (blockedObj3) {
183 System.out.println("BlockingThread attempts to notify c");
184 waitForBlocked(); // #4
185 }
186
187 } // run()
188 } // BlockingThread
189
190 private static long getBlockedCount() {
191 long count;
192 // Check the mbean now
193 ThreadInfo ti = mbean.getThreadInfo(blocked.getId());
194 count = ti.getBlockedCount();
195 return count;
196 }
197
198 private static boolean checkBlocked() {
199 // wait for the thread stats to be updated for 10 seconds
200 long count = -1;
201 for (int i = 0; i < 100; i++) {
202 count = getBlockedCount();
203 if (count >= EXPECTED_BLOCKED_COUNT) {
204 return true;
205 }
206 try {
207 Thread.sleep(100);
208 } catch (InterruptedException e) {
209 System.err.println("Unexpected exception.");
210 e.printStackTrace(System.err);
211 return false;
212 }
213 }
214 System.err.println("TEST FAILED: Blocked thread has " + count +
215 " blocked counts. Expected at least " +
216 EXPECTED_BLOCKED_COUNT);
217 return false;
218 }
219 }