1 /* 2 * Copyright (c) 1997, 2005, 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 /* @test 25 * @bug 4076287 26 * @summary Invoking get on a SoftReference shouldn't pin the referent 27 * @run main/othervm -ms16m -mx16m Pin 28 * @author Peter Jones 29 * @author Mark Reinhold 30 */ 31 32 33 import java.lang.ref.SoftReference; 34 35 public class Pin { 36 37 final static int NUM_BLOCKS = 128; 38 final static int BLOCK_SIZE = 32768; 39 main(String[] args)40 public static void main(String[] args) throws Exception { 41 42 SoftReference[] blocks = new SoftReference[NUM_BLOCKS]; 43 44 byte[] block; 45 46 System.err.println("Filling array with " + NUM_BLOCKS + 47 " SoftReferences to blocks of " + 48 BLOCK_SIZE + " bytes."); 49 50 for (int i = 0; i < NUM_BLOCKS; ++ i) { 51 block = new byte[BLOCK_SIZE]; 52 SoftReference ref = new SoftReference(block); 53 blocks[i] = ref; 54 } 55 block = null; 56 57 System.err.println("Allowing SoftReferences to be enqueued."); 58 System.gc(); 59 Thread.sleep(1000); 60 61 /* -- Commenting out the following section will hide the bug -- */ 62 System.err.println("Invoking get() on SoftReferences."); 63 for (int i = 0; i < NUM_BLOCKS; ++ i) { 64 block = (byte[]) blocks[i].get(); 65 } 66 block = null; 67 /* -- end -- */ 68 69 System.err.println("Forcing desperate garbage collection..."); 70 java.util.Vector chain = new java.util.Vector(); 71 try { 72 while (true) { 73 System.gc(); 74 int[] hungry = new int[65536]; 75 chain.addElement(hungry); 76 Thread.sleep(100); // yield, for what it's worth 77 } 78 } catch (OutOfMemoryError e) { 79 chain = null; // Free memory for further work. 80 System.err.println("Got OutOfMemoryError, as expected."); 81 } 82 83 int emptyCount = 0, fullCount = 0; 84 System.err.print("Examining contents of array:"); 85 for (int i = 0; i < NUM_BLOCKS; ++ i) { 86 block = (byte[]) blocks[i].get(); 87 if (block == null) { 88 emptyCount++; 89 } else { 90 fullCount++; 91 } 92 } 93 System.err.println(" " + emptyCount + " empty, " + 94 fullCount + " full."); 95 if (emptyCount == 0) 96 throw new Exception("No SoftReference instances were cleared"); 97 } 98 99 } 100