jdk-24/test/hotspot/jtreg/runtime/ClassUnload/UnloadTest.java
2023-03-03 16:44:27 +00:00

120 lines
4.8 KiB
Java

/*
* Copyright (c) 2013, 2023, 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 UnloadTest
* @bug 8210559 8297740
* @requires vm.opt.final.ClassUnloading
* @modules java.base/jdk.internal.misc
* @library /test/lib
* @library classes
* @build jdk.test.whitebox.WhiteBox test.Empty
* @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
* @run main/othervm -Xbootclasspath/a:. -Xmn8m -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xlog:class+unload=debug UnloadTest
*/
import jdk.test.whitebox.WhiteBox;
import jdk.test.lib.classloader.ClassUnloadCommon;
import java.lang.reflect.Array;
import java.lang.ref.Reference;
/**
* Test that verifies that liveness of classes is correctly tracked.
*
* The test creates a class loader, uses the loader to load a class and creates
* an instance related to that class.
* 1. Then, it nulls out references to the class loader, triggers class
* unloading and verifies the class is *not* unloaded.
* 2. Next, it nulls out references to the instance, triggers class unloading
* and verifies the class is unloaded.
*/
public class UnloadTest {
public static void main(String... args) throws Exception {
test_unload_instance_klass();
test_unload_obj_array_klass();
}
private static void test_unload_instance_klass() throws Exception {
final String className = "test.Empty";
final WhiteBox wb = WhiteBox.getWhiteBox();
ClassUnloadCommon.failIf(wb.isClassAlive(className), "is not expected to be alive yet");
ClassLoader cl = ClassUnloadCommon.newClassLoader();
Object o = cl.loadClass(className).newInstance();
ClassUnloadCommon.failIf(!wb.isClassAlive(className), "should be live here");
String loaderName = cl.getName();
int loadedRefcount = wb.getSymbolRefcount(loaderName);
System.out.println("Refcount of symbol " + loaderName + " is " + loadedRefcount);
cl = null;
ClassUnloadCommon.triggerUnloading();
ClassUnloadCommon.failIf(!wb.isClassAlive(className), "should still be live");
// Don't let `o` get prematurely reclaimed by the GC.
Reference.reachabilityFence(o);
o = null;
ClassUnloadCommon.triggerUnloading();
ClassUnloadCommon.failIf(wb.isClassAlive(className), "should have been unloaded");
int unloadedRefcount = wb.getSymbolRefcount(loaderName);
System.out.println("Refcount of symbol " + loaderName + " is " + unloadedRefcount);
ClassUnloadCommon.failIf(unloadedRefcount != (loadedRefcount - 1), "Refcount must be decremented");
}
private static void test_unload_obj_array_klass() throws Exception {
final WhiteBox wb = WhiteBox.getWhiteBox();
ClassLoader cl = ClassUnloadCommon.newClassLoader();
Object o = Array.newInstance(cl.loadClass("test.Empty"), 1);
final String className = o.getClass().getName();
ClassUnloadCommon.failIf(!wb.isClassAlive(className), "should be live here");
String loaderName = cl.getName();
int loadedRefcount = wb.getSymbolRefcount(loaderName);
System.out.println("Refcount of symbol " + loaderName + " is " + loadedRefcount);
cl = null;
ClassUnloadCommon.triggerUnloading();
ClassUnloadCommon.failIf(!wb.isClassAlive(className), "should still be live");
// Don't let `o` get prematurely reclaimed by the GC.
Reference.reachabilityFence(o);
o = null;
ClassUnloadCommon.triggerUnloading();
ClassUnloadCommon.failIf(wb.isClassAlive(className), "should have been unloaded");
int unloadedRefcount = wb.getSymbolRefcount(loaderName);
System.out.println("Refcount of symbol " + loaderName + " is " + unloadedRefcount);
ClassUnloadCommon.failIf(unloadedRefcount != (loadedRefcount - 1), "Refcount must be decremented");
}
}