77 lines
3.1 KiB
Java
77 lines
3.1 KiB
Java
/*
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* Copyright (c) 2013, 2021, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/*
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* @test UnloadTest
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* @bug 8210559
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* @requires vm.opt.final.ClassUnloading
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* @modules java.base/jdk.internal.misc
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* @library /test/lib
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* @library classes
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* @build sun.hotspot.WhiteBox test.Empty
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* @run driver jdk.test.lib.helpers.ClassFileInstaller sun.hotspot.WhiteBox
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* @run main/othervm -Xbootclasspath/a:. -Xmn8m -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xlog:class+unload=debug UnloadTest
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*/
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import sun.hotspot.WhiteBox;
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import jdk.test.lib.classloader.ClassUnloadCommon;
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/**
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* Test that verifies that classes are unloaded when they are no longer reachable.
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*
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* The test creates a class loader, uses the loader to load a class and creates an instance
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* of that class. The it nulls out all the references to the instance, class and class loader
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* and tries to trigger class unloading. Then it verifies that the class is no longer
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* loaded by the VM.
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*/
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public class UnloadTest {
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private static String className = "test.Empty";
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public static void main(String... args) throws Exception {
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run();
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}
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private static void run() throws Exception {
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final WhiteBox wb = WhiteBox.getWhiteBox();
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ClassUnloadCommon.failIf(wb.isClassAlive(className), "is not expected to be alive yet");
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ClassLoader cl = ClassUnloadCommon.newClassLoader();
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Class<?> c = cl.loadClass(className);
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Object o = c.newInstance();
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ClassUnloadCommon.failIf(!wb.isClassAlive(className), "should be live here");
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String loaderName = cl.getName();
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int loadedRefcount = wb.getSymbolRefcount(loaderName);
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System.out.println("Refcount of symbol " + loaderName + " is " + loadedRefcount);
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cl = null; c = null; o = null;
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ClassUnloadCommon.triggerUnloading();
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ClassUnloadCommon.failIf(wb.isClassAlive(className), "should have been unloaded");
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int unloadedRefcount = wb.getSymbolRefcount(loaderName);
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System.out.println("Refcount of symbol " + loaderName + " is " + unloadedRefcount);
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ClassUnloadCommon.failIf(unloadedRefcount != (loadedRefcount - 1), "Refcount must be decremented");
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}
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}
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