1 /*
2 * Copyright (c) 2003, 2015, 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
28 * RuntimeMXBean.getObjectPendingFinalizationCount()
29 * 1. GC and runFinalization() to get the current pending number
30 * 2. Create some number of objects with reference and without ref.
31 * 3. Clear all the references
32 * 4. GC and runFinalization() and the finalizable objects should
33 * be garbage collected.
34 * @author Alexei Guibadoulline and Mandy Chung
35 *
36 * @modules java.base/jdk.internal.misc
37 * java.management
38 */
39
40 import java.lang.management.*;
41
42 public class Pending {
43 static final int NO_REF_COUNT = 600;
44 static final int REF_COUNT = 500;
45 static final int TOTAL_FINALIZABLE = (NO_REF_COUNT + REF_COUNT);
46 private static int finalized = 0;
47 private static MemoryMXBean mbean
48 = ManagementFactory.getMemoryMXBean();
49
50 private static final String INDENT = " ";
51 private static void printFinalizerInstanceCount() {
52 if (!trace) return;
53
54 int count = jdk.internal.misc.VM.getFinalRefCount();
55 System.out.println(INDENT + "Finalizable object Count = " + count);
56
57 count = jdk.internal.misc.VM.getPeakFinalRefCount();
58 System.out.println(INDENT + "Peak Finalizable object Count = " + count);
59 }
60
61 private static boolean trace = false;
62 public static void main(String argv[]) throws Exception {
63 if (argv.length > 0 && argv[0].equals("trace")) {
64 trace = true;
65 }
66
67 try {
68 if (trace) {
69 // Turn on verbose:gc to track GC
70 mbean.setVerbose(true);
71 }
72 test();
73 } finally {
74 if (trace) {
75 mbean.setVerbose(false);
76 }
77 }
78 System.out.println("Test passed.");
79 }
80
81 // Keep objs public so the optimizer will not remove them too early.
82 public static Object[] objs = null;
83
84 private static void test() throws Exception {
85 // Clean the memory and remove all objects that are pending
86 // finalization
87 System.gc();
88 Snapshot snapshot = getSnapshotAfterFinalization();
89
90 System.out.println("Number of objects pending for finalization:");
91 System.out.println(" Before creating object: " + snapshot);
92 printFinalizerInstanceCount();
93
94 // Create objects without saving reference. Should be removed at next GC.
95 for (int i = 0; i < NO_REF_COUNT; i++) {
96 new MyObject();
97 }
98
99 snapshot = getSnapshot();
100 System.out.println(" Afer creating objects with no ref: " + snapshot);
101 printFinalizerInstanceCount();
102
103 // Create objects and save references.
104 objs = new Object[REF_COUNT];
105 for (int i = 0; i < REF_COUNT; i++) {
106 objs[i] = new MyObject();
107 }
108 snapshot = getSnapshot();
109 System.out.println(" Afer creating objects with ref: " + snapshot);
110 printFinalizerInstanceCount();
111
112 // Now check the expected count - GC and runFinalization will be
113 // invoked.
114 checkFinalizerCount(NO_REF_COUNT, 0);
115
116 // Clean the memory and remove all objects that are pending
117 // finalization again
118 objs = null;
119 snapshot = getSnapshot();
120 System.out.println("Clear all references finalized = " + snapshot);
121 printFinalizerInstanceCount();
122
123 checkFinalizerCount(TOTAL_FINALIZABLE, NO_REF_COUNT);
124
125 snapshot = getSnapshot();
126 printFinalizerInstanceCount();
127
128 // Check the mbean now
129 if (snapshot.curFinalized != TOTAL_FINALIZABLE) {
130 throw new RuntimeException("Wrong number of finalized objects "
131 + snapshot + ". Expected "
132 + TOTAL_FINALIZABLE);
133 }
134
135 if (snapshot.curPending != 0) {
136 throw new RuntimeException("Wrong number of objects pending "
137 + " end = " + snapshot);
138 }
139
140 }
141
142 private static void checkFinalizerCount(int expectedTotal, int curFinalized)
143 throws Exception {
144 int prevCount = -1;
145 Snapshot snapshot = getSnapshot();
146 if (snapshot.curFinalized != curFinalized) {
147 throw new RuntimeException(
148 "Unexpected finalized objects: " + snapshot +
149 " but expected = " + curFinalized);
150 }
151 int MAX_GC_LOOP = 6;
152 for (int i = 1;
153 snapshot.curFinalized != expectedTotal && i <= MAX_GC_LOOP;
154 i++) {
155 System.gc();
156 snapshot = getSnapshotAfterFinalization();
157
158 if (snapshot.curFinalized == expectedTotal &&
159 snapshot.curPending != 0) {
160 throw new RuntimeException(
161 "Unexpected current number of objects pending for " +
162 "finalization: " + snapshot + " but expected = 0");
163 }
164
165 System.out.println(" After runFinalization " + i + ": " + snapshot);
166 printFinalizerInstanceCount();
167
168 try {
169 Thread.sleep(1000);
170 } catch (Exception e) {
171 throw e;
172 }
173 }
174 if (snapshot.curFinalized != expectedTotal) {
175 throw new RuntimeException(
176 "Unexpected current number of objects pending for " +
177 "finalization: " + snapshot + " but expected > 0");
178 }
179 }
180
181 private static Object lock = new Object();
182 private static class MyObject {
183 Object[] dummy = new Object[10];
184 public void finalize () {
185 synchronized (lock) {
186 finalized++;
187 }
188 }
189 }
190
191 static class Snapshot {
192 public int curFinalized;
193 public int curPending;
194 Snapshot(int f, int p) {
195 curFinalized = f;
196 curPending = p;
197 }
198 public String toString() {
199 return "Current finalized = " + curFinalized +
200 " Current pending = " + curPending;
201 }
202 }
203
204 private static Snapshot getSnapshot() {
205 synchronized (lock) {
206 int curCount = mbean.getObjectPendingFinalizationCount();
207 return new Snapshot(finalized, curCount);
208 }
209 }
210
211 // Repeat getSnapshot until no pending finalization.
212 private static Snapshot getSnapshotAfterFinalization() throws Exception {
213 int loopCount = 0;
214 Snapshot snapshot = null;
215 while (loopCount < 100) {
216 Runtime.getRuntime().runFinalization();
217 Thread.sleep(50);
218 snapshot = getSnapshot();
219 if (snapshot.curPending == 0) {
220 return snapshot;
221 }
222 ++loopCount;
223 System.out.println("Waiting for curPending to be 0. snapshot=" + snapshot);
224 }
225 String msg = "Objects pending finalization is not 0. snapshot=%s";
226 throw new RuntimeException(String.format(msg, snapshot));
227 }
228 }