1 /*
   2  * Copyright (c) 2013, 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  * @library /runtime/testlibrary /testlibrary /testlibrary/whitebox
  27  * @library classes
  28  * @build ClassUnloadCommon test.Empty
  29  * @build UnloadTest
  30  * @run main ClassFileInstaller sun.hotspot.WhiteBox
  31  * @run main/othervm -Xbootclasspath/a:. -Xmn8m -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI UnloadTest
  32  */
  33 import sun.hotspot.WhiteBox;
  34 
  35 /**
  36  * Test that verifies that classes are unloaded when they are no longer reachable.
  37  *
  38  * The test creates a class loader, uses the loader to load a class and creates an instance
  39  * of that class. The it nulls out all the references to the instance, class and class loader
  40  * and tries to trigger class unloading. Then it verifies that the class is no longer
  41  * loaded by the VM.
  42  */
  43 public class UnloadTest {
  44     private static String className = "test.Empty";
  45 
  46     public static void main(String... args) throws Exception {
  47        run();
  48     }
  49 
  50     private static void run() throws Exception {
  51         final WhiteBox wb = WhiteBox.getWhiteBox();
  52 
  53         ClassUnloadCommon.failIf(wb.isClassAlive(className), "is not expected to be alive yet");
  54 
  55         ClassLoader cl = ClassUnloadCommon.newClassLoader();
  56         Class<?> c = cl.loadClass(className);
  57         Object o = c.newInstance();
  58 
  59         ClassUnloadCommon.failIf(!wb.isClassAlive(className), "should be live here");
  60 
  61         cl = null; c = null; o = null;
  62         ClassUnloadCommon.triggerUnloading();
  63         ClassUnloadCommon.failIf(wb.isClassAlive(className), "should have been unloaded");
  64     }
  65 }
  66