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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
* 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.
*/
/*
* This file is available under and governed by the GNU General Public
* License version 2 only, as published by the Free Software Foundation.
* However, the following notice accompanied the original version of this
* file:
*
* Written by Doug Lea and Martin Buchholz with assistance from members of
* JCP JSR-166 Expert Group and released to the public domain, as explained
* at http://creativecommons.org/publicdomain/zero/1.0/
*/
/*
* @test
* @summary Ensure that waiting pool threads don't retain refs to tasks.
*/
import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Delayed;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.RunnableScheduledFuture;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
public class GCRetention {
/**
* A custom thread pool with a custom RunnableScheduledFuture, for the
* sole purpose of ensuring that the task retains a strong reference to
* the Runnable even after cancellation.
*/
static class CustomPool extends ScheduledThreadPoolExecutor {
CustomPool(int n) { super(n); }
protected <V> RunnableScheduledFuture<V> decorateTask(
final Runnable r,
final RunnableScheduledFuture<V> task) {
return new RunnableScheduledFuture<V>() {
public void run() { System.err.println(r); task.run(); }
public boolean isPeriodic() { return task.isPeriodic(); }
public V get()
throws InterruptedException,ExecutionException
{ return task.get(); }
public V get(long x, TimeUnit y)
throws InterruptedException,ExecutionException,TimeoutException
{ return task.get(x, y); }
public boolean isDone() { return task.isDone(); }
public boolean isCancelled() { return task.isCancelled(); }
public boolean cancel(boolean x) { return task.cancel(x); }
public long getDelay(TimeUnit x) { return task.getDelay(x); }
public int compareTo(Delayed x) { return task.compareTo(x); }
};
}
}
void removeAll(ReferenceQueue<?> q, int n) throws InterruptedException {
for (int j = n; j--> 0; ) {
if (q.poll() == null) {
for (;;) {
System.gc();
if (q.remove(1000) != null)
break;
System.out.printf(
"%d/%d unqueued references remaining%n", j, n);
}
}
}
check(q.poll() == null);
}
void test(String[] args) throws Throwable {
final CustomPool pool = new CustomPool(10);
final int size = 100;
final ReferenceQueue<Object> q = new ReferenceQueue<>();
final List<WeakReference<?>> refs = new ArrayList<>(size);
final List<Future<?>> futures = new ArrayList<>(size);
// Schedule custom tasks with strong references.
class Task implements Runnable {
final Object x;
Task() { refs.add(new WeakReference<>(x = new Object(), q)); }
public void run() { System.out.println(x); }
}
// Give tasks added later earlier expiration, to ensure
// multiple residents of queue head.
for (int i = size; i--> 0; )
futures.add(pool.schedule(new Task(), i + 1, TimeUnit.MINUTES));
futures.forEach(future -> future.cancel(false));
futures.clear();
pool.purge();
removeAll(q, size);
for (WeakReference<?> ref : refs) check(ref.get() == null);
pool.shutdown();
// rely on test harness to handle timeout
pool.awaitTermination(1L, TimeUnit.DAYS);
}
//--------------------- Infrastructure ---------------------------
volatile int passed = 0, failed = 0;
void pass() {passed++;}
void fail() {failed++; Thread.dumpStack();}
void fail(String msg) {System.err.println(msg); fail();}
void unexpected(Throwable t) {failed++; t.printStackTrace();}
void check(boolean cond) {if (cond) pass(); else fail();}
void equal(Object x, Object y) {
if (x == null ? y == null : x.equals(y)) pass();
else fail(x + " not equal to " + y);}
public static void main(String[] args) throws Throwable {
new GCRetention().instanceMain(args);}
void instanceMain(String[] args) throws Throwable {
try {test(args);} catch (Throwable t) {unexpected(t);}
System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
if (failed > 0) throw new AssertionError("Some tests failed");}
}
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