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/*
* Copyright (c) 2015, 2025, 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.
*/
import jdk.test.whitebox.WhiteBox;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.ReentrantLock;
import java.lang.reflect.Method;
import java.lang.reflect.Field;
/*
* @test
* @summary Unit test for FinalizerHistogram
* @modules java.base/java.lang.ref:open
* @library /test/lib
* @build jdk.test.whitebox.WhiteBox
* @run driver jdk.test.lib.helpers.ClassFileInstaller jdk.test.whitebox.WhiteBox
* @run main/othervm
* -Xbootclasspath/a:.
* -XX:+UnlockDiagnosticVMOptions
* -XX:+WhiteBoxAPI
* FinalizerHistogramTest
*/
public class FinalizerHistogramTest {
static ReentrantLock lock = new ReentrantLock();
static final AtomicInteger initializedCount = new AtomicInteger(0);
static final int OBJECTS_COUNT = 1000;
static WhiteBox wb;
static class MyObject {
public MyObject() {
// Make sure object allocation/deallocation is not optimized out
initializedCount.incrementAndGet();
}
protected void finalize() {
// Trap the object in a finalization queue
lock.lock();
}
}
public static void main(String[] argvs) throws InterruptedException {
try {
lock.lock();
for(int i = 0; i < OBJECTS_COUNT; ++i) {
new MyObject();
}
System.out.println("Objects intialized: " + initializedCount.get());
wb = WhiteBox.getWhiteBox();
wb.fullGC();
boolean refProResult;
do {
refProResult = wb.waitForReferenceProcessing();
System.out.println("waitForReferenceProcessing returned: " + refProResult);
} while (refProResult);
Class<?> klass = Class.forName("java.lang.ref.FinalizerHistogram");
Method m = klass.getDeclaredMethod("getFinalizerHistogram");
m.setAccessible(true);
Object entries[] = (Object[]) m.invoke(null);
Class<?> entryKlass = Class.forName("java.lang.ref.FinalizerHistogram$Entry");
Field name = entryKlass.getDeclaredField("className");
name.setAccessible(true);
Field count = entryKlass.getDeclaredField("instanceCount");
count.setAccessible(true);
System.out.println("Unreachable instances waiting for finalization");
System.out.println("#instances class name");
System.out.println("-----------------------");
boolean found = false;
for (Object entry : entries) {
Object e = entryKlass.cast(entry);
System.out.printf("%10d %s\n", count.get(e), name.get(e));
if (((String) name.get(e)).indexOf("MyObject") != -1 ) {
found = true;
}
}
if (!found) {
throw new RuntimeException("MyObject is not found in test output");
}
System.out.println("Test PASSED");
} catch(Exception e) {
System.err.println("Test failed with " + e);
e.printStackTrace(System.err);
throw new RuntimeException("Test failed");
} finally {
lock.unlock();
}
}
}
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