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/*
* Copyright (c) 2022, 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 Make sure class unloading occur even if ClassLoaderStats VM operations are executed
* @bug 8297427
* @requires vm.opt.final.ClassUnloading
* @modules java.base/jdk.internal.misc
* @library /test/lib classes
* @build jdk.test.whitebox.WhiteBox test.Empty test.LoadInParent test.LoadInChild
* @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
* @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI -Xlog:gc*,class+unload=debug UnloadTestDuringClassLoaderStatsVMOperation
*/
import java.lang.ref.Reference;
import java.net.URLClassLoader;
import jdk.test.lib.classloader.ClassUnloadCommon;
import jdk.test.whitebox.WhiteBox;
public class UnloadTestDuringClassLoaderStatsVMOperation {
private static final WhiteBox wb = WhiteBox.getWhiteBox();
private static String className = "test.Empty";
private static String parentClassName = "test.LoadInParent";
private static String childClassName = "test.LoadInChild";
public static void main(String args[]) throws Exception {
// Create a thread forcing ClassLoaderStats VM operations.
var clsThread = new Thread(() -> {
while (true) {
wb.forceClassLoaderStatsSafepoint();
}
});
clsThread.setDaemon(true);
clsThread.start();
// Make sure classes can be unloaded even though the class loader
// stats VM operation is running.
testClassIsUnloaded();
testClassLoadedInParentIsUnloaded();
}
public static void testClassIsUnloaded() throws Exception {
ClassUnloadCommon.failIf(wb.isClassAlive(className), className + " is not expected to be alive yet");
// Load a test class and verify that it gets unloaded once we do a major collection.
var classLoader = ClassUnloadCommon.newClassLoader();
var loaded = classLoader.loadClass(className);
var object = loaded.getDeclaredConstructor().newInstance();
ClassUnloadCommon.failIf(!wb.isClassAlive(className), className + " should be loaded and live");
// Using reachabilityFence() to ensure the object is live. If the test
// is run with -Xcomp and ergonomically triggered GCs occur the class
// could otherwise be unloaded before verified to be alive above.
Reference.reachabilityFence(object);
System.out.println("testClassIsUnloaded loaded klass: " + className);
// Make class unloadable.
classLoader = null;
loaded = null;
object = null;
// Full/Major collection should always unload classes.
wb.fullGC();
ClassUnloadCommon.failIf(wb.isClassAlive(className), className + " should have been unloaded");
}
public static void testClassLoadedInParentIsUnloaded() throws Exception {
ClassUnloadCommon.failIf(wb.isClassAlive(parentClassName), parentClassName + " is not expected to be alive yet");
ClassUnloadCommon.failIf(wb.isClassAlive(childClassName), childClassName + " is not expected to be alive yet");
// Create two class loaders and load a test class in the parent and
// verify that it gets unloaded once we do a major collection.
var parentClassLoader = ClassUnloadCommon.newClassLoader();
var childClassLoader = new ChildURLClassLoader((URLClassLoader) parentClassLoader);
var loadedParent = parentClassLoader.loadClass(parentClassName);
var loadedChild = childClassLoader.loadClass(childClassName);
var parent = loadedParent.getDeclaredConstructor().newInstance();
var child = loadedChild.getDeclaredConstructor().newInstance();
ClassUnloadCommon.failIf(!wb.isClassAlive(parentClassName), parentClassName + " should be loaded and live");
ClassUnloadCommon.failIf(!wb.isClassAlive(childClassName), childClassName + " should be loaded and live");
// Using reachabilityFence() to ensure the objects are live. If the test
// is run with -Xcomp and ergonomically triggered GCs occur they could
// otherwise be unloaded before verified to be alive above.
Reference.reachabilityFence(parent);
Reference.reachabilityFence(child);
System.out.println("testClassLoadedInParentIsUnloaded loaded klass: " + loadedParent);
System.out.println("testClassLoadedInParentIsUnloaded loaded klass: " + loadedChild);
// Clear to allow unloading.
parentClassLoader = null;
childClassLoader = null;
loadedParent = null;
loadedChild = null;
parent = null;
child = null;
// Full/Major collection should always unload classes.
wb.fullGC();
ClassUnloadCommon.failIf(wb.isClassAlive(parentClassName), parentClassName + " should have been unloaded");
ClassUnloadCommon.failIf(wb.isClassAlive(childClassName), childClassName + " should have been unloaded");
}
static class ChildURLClassLoader extends URLClassLoader {
public ChildURLClassLoader(URLClassLoader parent) {
super("ChildURLClassLoader", parent.getURLs(), parent);
}
@Override
public Class<?> loadClass(String cn, boolean resolve) throws ClassNotFoundException {
synchronized (getClassLoadingLock(cn)) {
Class<?> c = findLoadedClass(cn);
if (c == null) {
try {
c = findClass(cn);
} catch (ClassNotFoundException e) {
c = getParent().loadClass(cn);
}
}
if (resolve) {
resolveClass(c);
}
return c;
}
}
}
}
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