1 /* 2 * Copyright (C) 2016 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 import java.lang.ref.WeakReference; 18 19 public class Main { 20 static final int numWeakReferences = 16 * 1024; 21 static WeakReference[] weakReferences = new WeakReference[numWeakReferences]; 22 static volatile boolean done = false; 23 static Object keepAlive; 24 25 public static void main(String[] args) throws Exception { 26 // Try to call Reference.get repeatedly while the GC is running. 27 Thread gcThread = new GcThread(); 28 Thread[] readerThread = new ReaderThread[4]; 29 for (int i = 0; i < readerThread.length; ++i) { 30 readerThread[i] = new ReaderThread(); 31 } 32 gcThread.start(); 33 for (int i = 0; i < readerThread.length; ++i) { 34 readerThread[i].start(); 35 } 36 gcThread.join(); 37 for (int i = 0; i < readerThread.length; ++i) { 38 readerThread[i].join(); 39 } 40 System.out.println("PASS"); 41 } 42 43 static class GcThread extends Thread { 44 GcThread() { 45 Object temp = new Object(); 46 for (int j = 0; j < weakReferences.length; ++j) { 47 weakReferences[j] = new WeakReference(temp); 48 } 49 } 50 public void run() { 51 for (int i = 0; i < 1000; ++i) { 52 Object o = new Object(); 53 for (int j = 0; j < weakReferences.length; ++j) { 54 weakReferences[j] = new WeakReference(o); 55 } 56 } 57 done = true; 58 } 59 } 60 61 static class ReaderThread extends Thread { 62 public void run() { 63 while (!done) { 64 for (int j = 0; j < weakReferences.length; ++j) { 65 keepAlive = weakReferences[j].get(); 66 } 67 for (int j = 0; j < weakReferences.length; ++j) { 68 weakReferences[j].clear(); 69 } 70 } 71 } 72 } 73 } 74
