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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
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* 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.
*
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*/
/*
* @test
* @bug 4530538
* @summary Basic unit test of
* RuntimeMXBean.getObjectPendingFinalizationCount()
* 1. GC and runFinalization() to get the current pending number
* 2. Create some number of objects with reference and without ref.
* 3. Clear all the references
* 4. GC and runFinalization() and the finalizable objects should
* be garbage collected.
* @author Alexei Guibadoulline and Mandy Chung
*
*/
import java.lang.management.*;
public class Pending {
final static int NO_REF_COUNT = 600;
final static int REF_COUNT = 600;
final static int TOTAL_FINALIZABLE = (NO_REF_COUNT + REF_COUNT);
private static int finalized = 0;
private static MemoryMXBean mbean
= ManagementFactory.getMemoryMXBean();
private static final String INDENT = " ";
private static void printFinalizerInstanceCount() {
if (!trace) return;
int count = sun.misc.VM.getFinalRefCount();
System.out.println(INDENT + "Finalizable object Count = " + count);
count = sun.misc.VM.getPeakFinalRefCount();
System.out.println(INDENT + "Peak Finalizable object Count = " + count);
}
private static boolean trace = false;
public static void main(String argv[]) throws Exception {
if (argv.length > 0 && argv[0].equals("trace")) {
trace = true;
}
try {
if (trace) {
// Turn on verbose:gc to track GC
mbean.setVerbose(true);
}
test();
} finally {
if (trace) {
mbean.setVerbose(false);
}
}
System.out.println("Test passed.");
}
private static void test() throws Exception {
// Clean the memory and remove all objects that are pending
// finalization
System.gc();
Runtime.getRuntime().runFinalization();
// Let the finalizer to finish
try {
Thread.sleep(200);
} catch (Exception e) {
throw e;
}
// Create a number of new objects but no references to them
int startCount = mbean.getObjectPendingFinalizationCount();
System.out.println("Number of objects pending for finalization:");
System.out.println(" Before creating object: " + startCount +
" finalized = " + finalized);
printFinalizerInstanceCount();
for (int i = 0; i < NO_REF_COUNT; i++) {
new MyObject();
}
Snapshot snapshot = getSnapshot();
System.out.println(" Afer creating objects with no ref: " + snapshot);
printFinalizerInstanceCount();
Object[] objs = new Object[REF_COUNT];
for (int i = 0; i < REF_COUNT; i++) {
objs[i] = new MyObject();
}
snapshot = getSnapshot();
System.out.println(" Afer creating objects with ref: " + snapshot);
printFinalizerInstanceCount();
// Now check the expected count - GC and runFinalization will be
// invoked.
checkFinalizerCount(NO_REF_COUNT, 0);
// Clean the memory and remove all objects that are pending
// finalization again
objs = null;
snapshot = getSnapshot();
System.out.println("Clear all references finalized = " + snapshot);
printFinalizerInstanceCount();
checkFinalizerCount(TOTAL_FINALIZABLE, NO_REF_COUNT);
snapshot = getSnapshot();
printFinalizerInstanceCount();
// Check the mbean now
if (snapshot.curFinalized != TOTAL_FINALIZABLE) {
throw new RuntimeException("Wrong number of finalized objects "
+ snapshot + ". Expected "
+ TOTAL_FINALIZABLE);
}
if (startCount != 0 || snapshot.curPending != 0) {
throw new RuntimeException("Wrong number of objects pending "
+ "finalization start = " + startCount
+ " end = " + snapshot);
}
}
private static void checkFinalizerCount(int expectedTotal, int curFinalized)
throws Exception {
int prevCount = -1;
Snapshot snapshot = getSnapshot();
if (snapshot.curFinalized != curFinalized) {
throw new RuntimeException(
"Unexpected finalized objects: " + snapshot +
" but expected = " + curFinalized);
}
int MAX_GC_LOOP = 6;
for (int i = 1;
snapshot.curFinalized != expectedTotal && i <= MAX_GC_LOOP;
i++) {
System.gc();
// Pause to give a chance to Finalizer thread to run
pause();
printFinalizerInstanceCount();
// Race condition may occur; attempt to check this
// a few times before throwing exception.
for (int j = 0; j < 5; j++) {
// poll for another current pending count
snapshot = getSnapshot();
if (snapshot.curFinalized == expectedTotal ||
snapshot.curPending != 0) {
break;
}
}
System.out.println(" After GC " + i + ": " + snapshot);
Runtime.getRuntime().runFinalization();
// Pause to give a chance to Finalizer thread to run
pause();
snapshot = getSnapshot();
if (snapshot.curFinalized == expectedTotal &&
snapshot.curPending != 0) {
throw new RuntimeException(
"Unexpected current number of objects pending for " +
"finalization: " + snapshot + " but expected = 0");
}
System.out.println(" After runFinalization " + i + ": " + snapshot);
printFinalizerInstanceCount();
try {
Thread.sleep(1000);
} catch (Exception e) {
throw e;
}
}
if (snapshot.curFinalized != expectedTotal) {
throw new RuntimeException(
"Unexpected current number of objects pending for " +
"finalization: " + snapshot + " but expected > 0");
}
}
private static Object lock = new Object();
private static class MyObject {
Object[] dummy = new Object[10];
public void finalize () {
synchronized (lock) {
finalized++;
}
}
}
static class Snapshot {
public int curFinalized;
public int curPending;
Snapshot(int f, int p) {
curFinalized = f;
curPending = p;
}
public String toString() {
return "Current finalized = " + curFinalized +
" Current pending = " + curPending;
}
}
private static Snapshot getSnapshot() {
synchronized (lock) {
int curCount = mbean.getObjectPendingFinalizationCount();
return new Snapshot(finalized, curCount);
}
}
private static Object pauseObj = new Object();
private static void pause() {
// Enter lock a without blocking
synchronized (pauseObj) {
try {
// may need to tune this timeout for different platforms
pauseObj.wait(20);
} catch (Exception e) {
System.err.println("Unexpected exception.");
e.printStackTrace(System.err);
}
}
}
}