/*
* Copyright (c) 1997, 2005, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/* @test
* @bug 4076287
* @summary Invoking get on a SoftReference shouldn't pin the referent
* @run main/othervm -ms16m -mx16m Pin
* @author Peter Jones
* @author Mark Reinhold
*/
import java.lang.ref.SoftReference;
public class Pin {
final static int NUM_BLOCKS = 128;
final static int BLOCK_SIZE = 32768;
public static void main(String[] args) throws Exception {
SoftReference[] blocks = new SoftReference[NUM_BLOCKS];
byte[] block;
System.err.println("Filling array with " + NUM_BLOCKS +
" SoftReferences to blocks of " +
BLOCK_SIZE + " bytes.");
for (int i = 0; i < NUM_BLOCKS; ++ i) {
block = new byte[BLOCK_SIZE];
SoftReference ref = new SoftReference(block);
blocks[i] = ref;
}
block = null;
System.err.println("Allowing SoftReferences to be enqueued.");
System.gc();
Thread.sleep(1000);
/* -- Commenting out the following section will hide the bug -- */
System.err.println("Invoking get() on SoftReferences.");
for (int i = 0; i < NUM_BLOCKS; ++ i) {
block = (byte[]) blocks[i].get();
}
block = null;
/* -- end -- */
System.err.println("Forcing desperate garbage collection...");
java.util.Vector chain = new java.util.Vector();
try {
while (true) {
System.gc();
int[] hungry = new int[65536];
chain.addElement(hungry);
Thread.sleep(100); // yield, for what it's worth
}
} catch (OutOfMemoryError e) {
System.err.println("Got OutOfMemoryError, as expected.");
}
int emptyCount = 0, fullCount = 0;
System.err.print("Examining contents of array:");
for (int i = 0; i < NUM_BLOCKS; ++ i) {
block = (byte[]) blocks[i].get();
if (block == null) {
emptyCount++;
} else {
fullCount++;
}
}
System.err.println(" " + emptyCount + " empty, " +
fullCount + " full.");
if (emptyCount == 0)
throw new Exception("No SoftReference instances were cleared");
}
}