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
40import java.lang.management.*;
41
42public 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}
229