1 /* 2 * Copyright (c) 2013, 2018, 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 /* 25 * @test UnloadTest 26 * @bug 8210559 27 * @requires vm.opt.final.ClassUnloading 28 * @modules java.base/jdk.internal.misc 29 * @library /runtime/testlibrary /test/lib 30 * @library classes 31 * @build sun.hotspot.WhiteBox test.Empty 32 * @run driver ClassFileInstaller sun.hotspot.WhiteBox 33 * sun.hotspot.WhiteBox$WhiteBoxPermission 34 * @run main/othervm -Xbootclasspath/a:. -Xmn8m -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xlog:class+unload=debug UnloadTest 35 */ 36 import sun.hotspot.WhiteBox; 37 38 /** 39 * Test that verifies that classes are unloaded when they are no longer reachable. 40 * 41 * The test creates a class loader, uses the loader to load a class and creates an instance 42 * of that class. The it nulls out all the references to the instance, class and class loader 43 * and tries to trigger class unloading. Then it verifies that the class is no longer 44 * loaded by the VM. 45 */ 46 public class UnloadTest { 47 private static String className = "test.Empty"; 48 main(String... args)49 public static void main(String... args) throws Exception { 50 run(); 51 } 52 run()53 private static void run() throws Exception { 54 final WhiteBox wb = WhiteBox.getWhiteBox(); 55 56 ClassUnloadCommon.failIf(wb.isClassAlive(className), "is not expected to be alive yet"); 57 58 ClassLoader cl = ClassUnloadCommon.newClassLoader(); 59 Class<?> c = cl.loadClass(className); 60 Object o = c.newInstance(); 61 62 ClassUnloadCommon.failIf(!wb.isClassAlive(className), "should be live here"); 63 64 String loaderName = cl.getName(); 65 int loadedRefcount = wb.getSymbolRefcount(loaderName); 66 System.out.println("Refcount of symbol " + loaderName + " is " + loadedRefcount); 67 68 cl = null; c = null; o = null; 69 ClassUnloadCommon.triggerUnloading(); 70 ClassUnloadCommon.failIf(wb.isClassAlive(className), "should have been unloaded"); 71 72 int unloadedRefcount = wb.getSymbolRefcount(loaderName); 73 System.out.println("Refcount of symbol " + loaderName + " is " + unloadedRefcount); 74 ClassUnloadCommon.failIf(unloadedRefcount != (loadedRefcount - 1), "Refcount must be decremented"); 75 } 76 } 77