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/*
* Copyright (c) 2021, 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.
*/
import java.lang.ref.Reference;
import java.lang.ref.WeakReference;
import java.io.ObjectStreamClass;
import java.io.Serializable;
import java.util.ArrayList;
import org.testng.annotations.Test;
import static org.testng.Assert.assertFalse;
import static org.testng.Assert.assertNotNull;
import static org.testng.Assert.assertNull;
import static org.testng.Assert.assertTrue;
/* @test
* @bug 8277072
* @library /test/lib/
* @summary ObjectStreamClass caches keep ClassLoaders alive
* @run testng/othervm -Xmx10m -XX:SoftRefLRUPolicyMSPerMB=1 ObjectStreamClassCaching
*/
public class ObjectStreamClassCaching {
@Test
public void testCachingEffectiveness() throws Exception {
var ref = lookupObjectStreamClass(TestClass.class);
System.gc();
Thread.sleep(100L);
// to trigger any ReferenceQueue processing...
lookupObjectStreamClass(AnotherTestClass.class);
assertNotNull(ref.get(), "Cache lost entry although memory was not under pressure");
}
@Test
public void testCacheReleaseUnderMemoryPressure() throws Exception {
var ref = lookupObjectStreamClass(TestClass.class);
pressMemoryHard(ref);
System.gc();
Thread.sleep(100L);
assertNull(ref.get(), "Cache still has entry although memory was pressed hard");
}
// separate method so that the looked-up ObjectStreamClass is not kept on stack
private static WeakReference<?> lookupObjectStreamClass(Class<?> cl) {
return new WeakReference<>(ObjectStreamClass.lookup(cl));
}
private static void pressMemoryHard(Reference<?> ref) {
try {
var list = new ArrayList<>();
while (ref.get() != null) {
list.add(new byte[1024 * 1024 * 64]); // 64 MiB chunks
}
} catch (OutOfMemoryError e) {
// release
}
}
}
class TestClass implements Serializable {
}
class AnotherTestClass implements Serializable {
}
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