Main.java revision e0e29754397bc0447d77d8cc82009d83ffb01208 
1/*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17/**
18 * Running concurrent gc and doing some System.arraycopy
19 * Several threads is created in order to increase the probability
20 * of thread switches at critical points. Without creating several
21 * threads the test case usually passed even when there were bugs.
22 * Size of array and amount of garbage created is based on experimental
23 * numbers and is a tradeoff between time that the test takes when
24 * it succeeds and the probability that the test discovers a problem.
25 */
26public class Main {
27    public static void main(String args[]) {
28        new ObjectCreatorThread(true).start();
29        new ObjectCreatorThread(false).start();
30        new ObjectCreatorThread(false).start();
31    }
32
33    static class ObjectCreatorThread extends Thread {
34        boolean mDoLog;
35        public ObjectCreatorThread(boolean doLog) {
36            mDoLog = doLog;
37        }
38
39        @Override
40        public void run() {
41            new Main().stressArray(mDoLog);
42        }
43    }
44
45    Object [] array = new Object[10000];
46
47    void stressArray(boolean doLog) {
48        // We want many references in the array
49        // We also want elements close to each other to have large
50        // diff in address so lets skip every 2:nd address so it is null
51        if (doLog) {
52            System.out.println("Initializing...");
53        }
54        for (int i = 0; i < array.length; i+=2) {
55            array[i] = new String("Creating some garbage" + i);
56        }
57
58        if (doLog) {
59            System.out.println("Starting the test");
60        }
61
62        for (int j = 0; j < array.length; j++) {
63            Object obj = array[array.length - 1];
64            System.arraycopy(array, 0, array, 1, array.length - 1);
65            array[0] = obj;
66            new String("Creating some garbage" + Math.random());
67            new String("Creating some garbage" + Math.random());
68            new String("Creating some garbage" + Math.random());
69            new String("Creating some garbage" + Math.random());
70        }
71
72        for (int j = 0; j < array.length; j++) {
73            Object obj = array[0];
74            System.arraycopy(array, 1, array, 0, array.length - 1);
75            array[array.length - 1] = obj;
76            new String("Creating some garbage" + Math.random());
77            new String("Creating some garbage" + Math.random());
78            new String("Creating some garbage" + Math.random());
79            new String("Creating some garbage" + Math.random());
80        }
81
82        if (doLog) {
83            System.out.println("Test OK");
84        }
85    }
86}
87