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 */ 26 public 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
