1 /*
2 * Copyright (c) 2008, 2018, 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
26 /*
27 * @test
28 * @key stress gc
29 *
30 * @summary converted from VM Testbase gc/hashcode/ExternalHashingTest.
31 * VM Testbase keywords: [gc, stress, stressopt, nonconcurrent, jrockit]
32 * VM Testbase readme:
33 * DESCRIPTION
34 * Test the possible interaction of external hashing and locking on object
35 * headers.
36 * The approach is to nearly simultaneously lock/hash a relatively small group
37 * of objects. We do this repeatedly (munging), recording all hash values
38 * collected therein.
39 * After doing this for a large number of groups, we force a garbage collection,
40 * which would change the hashCode of an object if it hasn't previously been
41 * hashed. In our case, we _know_ what the previous hashcode was, so we can
42 * recalculate all of their hashes and compare with the original value.
43 * If any of the hashCodes hash changed, we know we have a problem.
44 *
45 * COMMENTS
46 * This test was ported from JRockit test suite.
47 *
48 * @library /vmTestbase
49 * /test/lib
50 * @run driver jdk.test.lib.FileInstaller . .
51 * @run main/othervm -XX:-UseGCOverheadLimit gc.hashcode.ExternalHashingTest.ExternalHashingTest
52 */
53
54 package gc.hashcode.ExternalHashingTest;
55
56 import java.text.SimpleDateFormat;
57 import java.util.Date;
58 import java.util.Random;
59 import java.util.Vector;
60
61 import jdk.test.lib.Utils;
62
63 /**
64 * Test the possible interaction of external hashing and locking on object
65 * headers.
66 *
67 * The approach is to nearly simultaneously lock/hash a relatively small group
68 * of objects. We do this repeatedly (munging), recording all hash values
69 * collected therein.
70 *
71 * After doing this for a large number of groups, we force a garbage collection,
72 * which would change the hashCode of an object if it hasn't previously been
73 * hashed. In our case, we _know_ what the previous hashcode was, so we can
74 * recalculate all of their hashes and compare with the original value.
75 *
76 * If any of the hashCodes hash changed, we know we have a problem.
77 */
78
79 public final class ExternalHashingTest {
80
81 /** Random number generator. */
82 static Random rand = Utils.getRandomInstance();
83
84 /** Goes to true when the threads should start working. */
85 public static volatile boolean startingGun;
86
87 /** Goes to true when the hashing thread is done. */
88 public static volatile boolean finishHashing;
89
90 /** Goes to true when the locking thread is done. */
91 public static volatile boolean finishLocking;
92
93 /** The number of objects in each batch. */
94 private static final int BATCH_SIZE = 20;
95
96 /** This is the global list of objects that have been hashed. */
97 static Vector allObjects = new Vector();
98
99 /** This is the corresponding list of hashCodes collected. */
100 static Vector allHashes = new Vector();
101
102 /** The default milliseconds to run the program. */
103 private static final long DEFAULT_DURATION = 10000;
104
105 /** All static */
106 private ExternalHashingTest() {}
107
108 /**
109 * This object holds garbage. It is a (probably unnecessary){ embellishment
110 * to increase the amount of garbage created by this benchmark.
111 * <p>
112 * It is global to discourage optimizer from removing it.
113 */
114 public static Object[] garbageMonger;
115
116 /**
117 * We need a fairly short pause, since we're not using a semaphore to
118 * synchronize threads.
119 */
120 public static void pause() {
121 try {
122 // Thread.sleep(100);
123 Thread.yield();
124 } catch (Exception e) {
125 e.printStackTrace();
126 System.exit(1);
127 }
128 }
129
130 /**
131 * Returns System.currentTimeMillis() in the Date format.
132 * @return String
133 */
134 private static String getDateString() {
135 SimpleDateFormat df = new SimpleDateFormat("MMM dd, yyyy HH:mm:ss z");
136 Date date = new Date();
137 date.setTime(System.currentTimeMillis());
138 return df.format(date);
139 }
140
141 /**
142 * Main driver.
143 * @param args command line arguments aren't used.
144 */
145 public static void main(String[] args) {
146
147 long timeToRun = DEFAULT_DURATION;;
148
149 try {
150 for (int i = 0; i < args.length; i++) {
151 if ("-stressTime".equals(args[i])) {
152 if (i + 1 == args.length) {
153 throw new RuntimeException("Test bug: value of -stressTime option absents");
154 }
155 timeToRun = Long.parseLong(args[i + 1]);
156 if (timeToRun <= 0) {
157 throw new RuntimeException("Test bug: value of -stressTime option is not a positive number");
158 }
159 break;
160 }
161 }
162 } catch (NumberFormatException e) {
163 throw new RuntimeException("Test bug: Exception occured while parsing -stressTime option's value", e);
164 }
165
166 long startTime = System.currentTimeMillis();
167
168 System.out.println("[" + getDateString() + "] Test duration is: " + timeToRun + " ms");
169 System.out.println("[" + getDateString() + "] Do munge objects...");
170 while ((System.currentTimeMillis() - startTime) < timeToRun) {
171 for (int i = 0; i < 100; i++) {
172 mungeObjects();
173 }
174 System.out.println("[" + getDateString() + "] The next 100 objects are munged...");
175 }
176
177 // Force a GC (so that objects move their position)
178 System.out.println("[" + getDateString() + "] Force a GC...");
179 garbageMonger = null;
180 System.gc();
181
182 // Now, to check to see if hashes are correct
183 System.out.println("[" + getDateString() + "] Check hash codes...");
184 for (int i = 0; i < allObjects.size(); i++) {
185 Object o = allObjects.elementAt(i);
186 int hash = ((Integer) allHashes.elementAt(i)).intValue();
187
188 if (o.hashCode() != hash) {
189 System.out.println("Inconsistent hash code found (Object "
190 + i + " out of " + allObjects.size());
191 System.out.println("Object = " + o.toString() + "; hashCode = 0x"
192 + Integer.toHexString(o.hashCode())
193 + "; expected = 0x" + Integer.toHexString(hash));
194 System.exit(1);
195 }
196 }
197
198 System.exit(95 /* PASSED */);
199 }
200
201 /**
202 * Add a single batch of objects to the mix.
203 * <p>
204 * It prepares a list of candidate objects, and presents them to a
205 * LockerThread and a HasherThread in randomized orders.
206 * <p>
207 * The two threads are launched, and control is returned to the caller after
208 * they have finished their processing.
209 */
210 private static void mungeObjects() {
211
212 startingGun = false;
213 finishHashing = false;
214 finishLocking = false;
215
216 /* Create the list of victims. */
217 Object[] candidates = new Object[BATCH_SIZE];
218 for (int i = 0; i < candidates.length; i++) {
219 candidates[i] = new Object();
220 }
221
222 Object[] lockedList = randomize(candidates);
223 Object[] hashedList = randomize(candidates);
224 int[] foundHashes = new int[BATCH_SIZE];
225
226 // Launch the child threads
227 LockerThread locker = new LockerThread(lockedList);
228 Thread lockerThread = new Thread(locker);
229 Thread hasherThread = new Thread(new HasherThread(hashedList,
230 foundHashes));
231 lockerThread.start();
232 hasherThread.start();
233 startingGun = true;
234
235 while (!finishLocking || !finishHashing) {
236 pause();
237 }
238
239 garbageMonger = new Object[BATCH_SIZE];
240 for (int i = 0; i < BATCH_SIZE; i++) {
241 /* Add all of the results of this pass to the global list. */
242 allObjects.add(hashedList[i]);
243 allHashes.add(new Integer(foundHashes[i]));
244
245 /* Create even more garbage for the GC to find */
246 garbageMonger[i] = new Object();
247 }
248
249 // just some noise to make sure that do-nothing code is not optimized
250 // away.
251 if (locker.getCount() != BATCH_SIZE) {
252 throw new InternalError("should not get here");
253 }
254 }
255
256 /**
257 * Return the list of objects in random order
258 */
259 private static Object[] randomize(Object[] list) {
260
261 Vector v = new Vector();
262 for (int i = 0; i < list.length; i++) {
263 v.add(list[i]);
264 }
265
266 Object[] result = new Object[list.length];
267 for (int i = 0; i < list.length; i++) {
268 int pos = rand.nextInt(list.length - i);
269 result[i] = v.remove(pos);
270 }
271 return result;
272 }
273 }
274
275 /**
276 * This helper thread locks all objects in a list in a given order before
277 * returning.
278 */
279
280 class LockerThread implements Runnable {
281
282 /** The list of objects to be locked. */
283 Object[] theList;
284
285 /**
286 * This junk counter is an attempt to cause the contents of the synchronized
287 * block not to be completely optimized away.
288 */
289 int count;
290
291 /**
292 * Construct a LockerThread and provide a list of objects to work with.
293 * @param list the objects to lock.
294 */
295 LockerThread(Object[] list) {
296 theList = list;
297 count = 0;
298 }
299
300 /**
301 * Proceed to lock the objects...
302 */
303 public void run() {
304 // Synchronize. Wait for caller to say all is go.
305 while (!ExternalHashingTest.startingGun) {
306 ExternalHashingTest.pause();
307 }
308
309 // Perform the locking
310 for (int i = 0; i < theList.length; i++) {
311 synchronized (theList[i]) {
312 count++;
313 }
314 }
315
316 // Tell the caller we are done.
317 ExternalHashingTest.finishLocking = true;
318 }
319
320 /**
321 * Discourage compiler from removing do-nothing count field.
322 * @return the number of objects locked.
323 */
324 public int getCount() {
325 return count;
326 }
327 }
328
329 /**
330 * This helper thread hashes all objects in a list in a given order before
331 * returning.
332 */
333
334 class HasherThread implements Runnable {
335
336 /** The list of objects to be hashed. */
337 Object[] theList;
338
339 /** The list of hash codes. */
340 int[] theHashes;
341
342 /**
343 * Construct a HasherThread and provide a list of objects to work with.
344 * @param list the objects to hash.
345 * @param hashes for storing the hash values.
346 */
347 HasherThread(Object[] list, int[] hashes) {
348 theList = list;
349 theHashes = hashes;
350 }
351
352 /**
353 * Proceed to hash the objects.
354 */
355 public void run() {
356 // Synchronize. Wait for caller to say all is go.
357 while (!ExternalHashingTest.startingGun) {
358 ExternalHashingTest.pause();
359 }
360
361 // Perform the hashing (collect for the caller)
362 for (int i = 0; i < theList.length; i++) {
363 theHashes[i] = theList[i].hashCode();
364 }
365 // Tell the caller we are done.
366 ExternalHashingTest.finishHashing = true;
367 }
368 }