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
|
/*
* Copyright (c) 2025, 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.
*/
/*
* @test
* @bug 8351230
* @summary Test that List's new SequencedCollection methods are properly
* synchronized on a synchronized list.
* @library /test/lib
* @build jdk.test.lib.Utils
* @run main SyncListBash f
* @run main SyncListBash r
*/
import java.util.*;
import java.util.concurrent.*;
import java.util.stream.*;
import jdk.test.lib.Utils;
public class SyncListBash {
static final int LOOP_COUNT = 1000;
static final int NUM_WORKERS = 4;
static List<Integer> list;
/**
* Test for race conditions with synchronized lists. Several worker threads
* add and remove elements from the front of the list, while the main thread
* gets the last element. The last element should never change. However, if
* the list isn't properly synchronized, getLast() might return the wrong
* element or throw IndexOutOfBoundsException.
*
* On an unsynchronized list, this fails 200-500 out of 1000 times, so this
* seems like a fairly reliable way to test for a race condition.
*
* @param args there must be one arg, "f" or "r", which determines whether the
* forward (original) list or reversed view of the list is tested
* @throws InterruptedException if the main thread is interrupted
*/
public static void main(String[] args) throws InterruptedException {
int wrongElement = 0;
int numExceptions = 0;
boolean reversed = switch (args[0]) {
case "f" -> false;
case "r" -> true;
default -> throw new IllegalArgumentException();
};
list = IntStream.range(0, 10)
.boxed()
.collect(Collectors.toCollection(ArrayList::new));
list = Collections.synchronizedList(list);
if (reversed)
list = list.reversed();
Integer expectedLast = list.getLast();
ExecutorService pool = Executors.newFixedThreadPool(NUM_WORKERS);
for (int i = 0; i < NUM_WORKERS; i++)
pool.submit(() -> {
while (! Thread.currentThread().isInterrupted()) {
list.add(0, -1);
list.remove(0);
}
});
for (int i = 0; i < LOOP_COUNT; i++) {
Thread.sleep(1L);
try {
Integer actualLast = list.getLast();
if (! expectedLast.equals(actualLast)) {
++wrongElement;
}
} catch (IndexOutOfBoundsException ioobe) {
++numExceptions;
}
}
pool.shutdownNow();
pool.awaitTermination(Utils.adjustTimeout(60L), TimeUnit.SECONDS);
System.out.printf("LOOP_COUNT=%d wrongElement=%d numExceptions=%d%n",
LOOP_COUNT, wrongElement, numExceptions);
if (wrongElement == 0 && numExceptions == 0) {
System.out.println("Test passed.");
} else {
throw new AssertionError("TEST FAILED!");
}
}
}
|
