1 /*
2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 */
22
23 /*
24 * This file is available under and governed by the GNU General Public
25 * License version 2 only, as published by the Free Software Foundation.
26 * However, the following notice accompanied the original version of this
27 * file:
28 *
29 * Written by Doug Lea and Martin Buchholz with assistance from members of
30 * JCP JSR-166 Expert Group and released to the public domain, as explained
31 * at http://creativecommons.org/publicdomain/zero/1.0/
32 */
33
34 /*
35 * @test
36 * @summary Ensure that waiting pool threads don't retain refs to tasks.
37 */
38
39 import java.lang.ref.ReferenceQueue;
40 import java.lang.ref.WeakReference;
41 import java.util.ArrayList;
42 import java.util.List;
43 import java.util.concurrent.Delayed;
44 import java.util.concurrent.ExecutionException;
45 import java.util.concurrent.Future;
46 import java.util.concurrent.RunnableScheduledFuture;
47 import java.util.concurrent.ScheduledThreadPoolExecutor;
48 import java.util.concurrent.TimeUnit;
49 import java.util.concurrent.TimeoutException;
50
51 public class GCRetention {
52
53 /**
54 * A custom thread pool with a custom RunnableScheduledFuture, for the
55 * sole purpose of ensuring that the task retains a strong reference to
56 * the Runnable even after cancellation.
57 */
58 static class CustomPool extends ScheduledThreadPoolExecutor {
59 CustomPool(int n) { super(n); }
60 protected <V> RunnableScheduledFuture<V> decorateTask(
61 final Runnable r,
62 final RunnableScheduledFuture<V> task) {
63 return new RunnableScheduledFuture<V>() {
64 public void run() { System.err.println(r); task.run(); }
65 public boolean isPeriodic() { return task.isPeriodic(); }
66 public V get()
67 throws InterruptedException,ExecutionException
68 { return task.get(); }
69 public V get(long x, TimeUnit y)
70 throws InterruptedException,ExecutionException,TimeoutException
71 { return task.get(x, y); }
72 public boolean isDone() { return task.isDone(); }
73 public boolean isCancelled() { return task.isCancelled(); }
74 public boolean cancel(boolean x) { return task.cancel(x); }
75 public long getDelay(TimeUnit x) { return task.getDelay(x); }
76 public int compareTo(Delayed x) { return task.compareTo(x); }
77 };
78 }
79 }
80
81 void removeAll(ReferenceQueue<?> q, int n) throws InterruptedException {
82 for (int j = n; j--> 0; ) {
83 if (q.poll() == null) {
84 for (;;) {
85 System.gc();
86 if (q.remove(1000) != null)
87 break;
88 System.out.printf(
89 "%d/%d unqueued references remaining%n", j + 1, n);
90 }
91 }
92 }
93 check(q.poll() == null);
94 }
95
96 void test(String[] args) throws Throwable {
97 final CustomPool pool = new CustomPool(10);
98 final int size = 100;
99 final ReferenceQueue<Object> q = new ReferenceQueue<>();
100 final List<WeakReference<?>> refs = new ArrayList<>(size);
101 final List<Future<?>> futures = new ArrayList<>(size);
102
103 // Schedule custom tasks with strong references.
104 class Task implements Runnable {
105 final Object x;
106 Task() { refs.add(new WeakReference<>(x = new Object(), q)); }
107 public void run() { System.out.println(x); }
108 }
109 // Give tasks added later earlier expiration, to ensure
110 // multiple residents of queue head.
111 for (int i = size; i--> 0; )
112 futures.add(pool.schedule(new Task(), i + 1, TimeUnit.MINUTES));
113 futures.forEach(future -> future.cancel(false));
114 futures.clear();
115
116 pool.purge();
117 removeAll(q, size);
118 for (WeakReference<?> ref : refs) check(ref.get() == null);
119
120 pool.shutdown();
121 // rely on test harness to handle timeout
122 pool.awaitTermination(1L, TimeUnit.DAYS);
123 }
124
125 //--------------------- Infrastructure ---------------------------
126 volatile int passed = 0, failed = 0;
127 void pass() {passed++;}
128 void fail() {failed++; Thread.dumpStack();}
129 void fail(String msg) {System.err.println(msg); fail();}
130 void unexpected(Throwable t) {failed++; t.printStackTrace();}
131 void check(boolean cond) {if (cond) pass(); else fail();}
132 void equal(Object x, Object y) {
133 if (x == null ? y == null : x.equals(y)) pass();
134 else fail(x + " not equal to " + y);}
135 public static void main(String[] args) throws Throwable {
136 new GCRetention().instanceMain(args);}
137 void instanceMain(String[] args) throws Throwable {
138 try {test(args);} catch (Throwable t) {unexpected(t);}
139 System.out.printf("%nPassed = %d, failed = %d%n%n", passed, failed);
140 if (failed > 0) throw new AssertionError("Some tests failed");}
141 }