1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
|
/*
* Copyright (c) 2005, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* 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
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* @summary SynchronizerDeadlock creates threads that are deadlocked
* waiting for JSR-166 synchronizers.
* @author Mandy Chung
* @build Barrier
*/
import java.lang.management.*;
import java.util.*;
import java.util.concurrent.locks.*;
public class SynchronizerDeadlock {
private Lock a = new ReentrantLock();
private Lock b = new ReentrantLock();
private Lock c = new ReentrantLock();
private final int EXPECTED_THREADS = 3;
private Thread[] dThreads = new Thread[EXPECTED_THREADS];
private Barrier go = new Barrier(1);
private Barrier barr = new Barrier(EXPECTED_THREADS);
public SynchronizerDeadlock() {
dThreads[0] = new DeadlockingThread("Deadlock-Thread-1", a, b);
dThreads[1] = new DeadlockingThread("Deadlock-Thread-2", b, c);
dThreads[2] = new DeadlockingThread("Deadlock-Thread-3", c, a);
// make them daemon threads so that the test will exit
for (int i = 0; i < EXPECTED_THREADS; i++) {
dThreads[i].setDaemon(true);
dThreads[i].start();
}
}
void goDeadlock() {
// Wait until all threads have started
barr.await();
// reset for later signals
barr.set(EXPECTED_THREADS);
while (go.getWaiterCount() != EXPECTED_THREADS) {
synchronized(this) {
try {
wait(100);
} catch (InterruptedException e) {
// ignore
}
}
}
// sleep a little so that all threads are blocked before notified.
try {
Thread.sleep(100);
} catch (InterruptedException e) {
// ignore
}
go.signal();
}
void waitUntilDeadlock() {
barr.await();
for (int i=0; i < 100; i++) {
// sleep a little while to wait until threads are blocked.
try {
Thread.sleep(100);
} catch (InterruptedException e) {
// ignore
}
boolean retry = false;
for (Thread t: dThreads) {
if (t.getState() == Thread.State.RUNNABLE) {
retry = true;
break;
}
}
if (!retry) {
break;
}
}
}
private class DeadlockingThread extends Thread {
private final Lock lock1;
private final Lock lock2;
DeadlockingThread(String name, Lock lock1, Lock lock2) {
super(name);
this.lock1 = lock1;
this.lock2 = lock2;
}
public void run() {
f();
}
private void f() {
lock1.lock();
try {
barr.signal();
go.await();
g();
} finally {
lock1.unlock();
}
}
private void g() {
barr.signal();
lock2.lock();
throw new RuntimeException("should not reach here.");
}
}
void checkResult(long[] threads) {
if (threads.length != EXPECTED_THREADS) {
ThreadDump.threadDump();
throw new RuntimeException("Expected to have " +
EXPECTED_THREADS + " to be in the deadlock list");
}
boolean[] found = new boolean[EXPECTED_THREADS];
for (int i = 0; i < threads.length; i++) {
for (int j = 0; j < dThreads.length; j++) {
if (dThreads[j].getId() == threads[i]) {
found[j] = true;
}
}
}
boolean ok = true;
for (int j = 0; j < found.length; j++) {
ok = ok && found[j];
}
if (!ok) {
System.out.print("Returned result is [");
for (int j = 0; j < threads.length; j++) {
System.out.print(threads[j] + " ");
}
System.out.println("]");
System.out.print("Expected result is [");
for (int j = 0; j < threads.length; j++) {
System.out.print(dThreads[j] + " ");
}
System.out.println("]");
throw new RuntimeException("Unexpected result returned " +
" by findMonitorDeadlockedThreads method.");
}
}
}
|
