1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
|
/*
* Copyright (c) 2006, 2023, 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
* @bug 6399443 8302899
* @summary Test that Executors.newSingleThreadExecutor wraps an ExecutorService that
* automatically shuts down and terminates when the wrapper is GC'ed
* @modules java.base/java.util.concurrent:+open
* @run junit AutoShutdown
*/
import java.lang.reflect.Field;
import java.time.Duration;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.Supplier;
import java.util.stream.Stream;
import java.util.stream.IntStream;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.MethodSource;
import org.junit.jupiter.params.provider.Arguments;
import static org.junit.jupiter.api.Assertions.*;
class AutoShutdown {
private static Stream<Supplier<ExecutorService>> executors() {
return Stream.of(
() -> Executors.newSingleThreadExecutor(),
() -> Executors.newSingleThreadExecutor(Executors.defaultThreadFactory())
);
}
private static Stream<Arguments> executorAndQueuedTaskCounts() {
int[] queuedTaskCounts = { 0, 1, 2 };
return executors().flatMap(s -> IntStream.of(queuedTaskCounts)
.mapToObj(i -> Arguments.of(s, i)));
}
/**
* SingleThreadExecutor with no worker threads.
*/
@ParameterizedTest
@MethodSource("executors")
void testNoWorker(Supplier<ExecutorService> supplier) throws Exception {
ExecutorService executor = supplier.get();
ExecutorService delegate = getDelegate(executor);
executor = null;
gcAndAwaitTermination(delegate);
}
/**
* SingleThreadExecutor with an idle worker thread.
*/
@ParameterizedTest
@MethodSource("executors")
void testIdleWorker(Supplier<ExecutorService> supplier) throws Exception {
ExecutorService executor = supplier.get();
// submit a task to get a worker to start
executor.submit(() -> null).get();
ExecutorService delegate = getDelegate(executor);
executor = null;
gcAndAwaitTermination(delegate);
}
/**
* SingleThreadExecutor with an active worker and queued tasks.
*/
@ParameterizedTest
@MethodSource("executorAndQueuedTaskCounts")
void testActiveWorker(Supplier<ExecutorService> supplier,int queuedTaskCount) throws Exception {
ExecutorService executor = supplier.get();
// the worker will execute one task, the other tasks will be queued
int ntasks = 1 + queuedTaskCount;
AtomicInteger completedTaskCount = new AtomicInteger();
for (int i = 0; i < ntasks; i++) {
executor.submit(() -> {
Thread.sleep(Duration.ofMillis(500));
completedTaskCount.incrementAndGet();
return null;
});
}
ExecutorService delegate = getDelegate(executor);
executor = null;
gcAndAwaitTermination(delegate);
assertEquals(ntasks, completedTaskCount.get());
}
/**
* Returns the delegate for the given ExecutorService. The given ExecutorService
* must be a Executors$DelegatedExecutorService.
*/
private ExecutorService getDelegate(ExecutorService executor) throws Exception {
Field eField = Class.forName("java.util.concurrent.Executors$DelegatedExecutorService")
.getDeclaredField("e");
eField.setAccessible(true);
return (ExecutorService) eField.get(executor);
}
/**
* Invokes System.gc and waits for the given ExecutorService to terminate.
*/
private void gcAndAwaitTermination(ExecutorService executor) throws Exception {
System.err.println(executor);
boolean terminated = false;
while (!terminated) {
System.gc();
terminated = executor.awaitTermination(100, TimeUnit.MILLISECONDS);
}
}
}
|
