File: UnreferencedMulticastSockets.java

package info (click to toggle)
openjdk-11 11.0.4%2B11-1
  • links: PTS, VCS
  • area: main
  • in suites: sid
  • size: 757,028 kB
  • sloc: java: 5,016,041; xml: 1,191,974; cpp: 934,731; ansic: 555,697; sh: 24,299; objc: 12,703; python: 3,602; asm: 3,415; makefile: 2,772; awk: 351; sed: 172; perl: 114; jsp: 24; csh: 3
file content (271 lines) | stat: -rw-r--r-- 10,183 bytes parent folder | download | duplicates (2)
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
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
/*
 * Copyright (c) 2018, 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
 * @modules java.management java.base/java.io:+open java.base/java.net:+open
 * @run main/othervm -Djava.net.preferIPv4Stack=true UnreferencedMulticastSockets
 * @run main/othervm UnreferencedMulticastSockets
 * @summary Check that unreferenced multicast sockets are closed
 */

import java.io.FileDescriptor;
import java.lang.management.ManagementFactory;
import java.lang.management.OperatingSystemMXBean;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import java.lang.reflect.Field;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.DatagramSocketImpl;
import java.net.InetAddress;
import java.net.MulticastSocket;
import java.net.UnknownHostException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayDeque;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.TimeUnit;

import com.sun.management.UnixOperatingSystemMXBean;

public class UnreferencedMulticastSockets {

    /**
     * The set of sockets we have to check up on.
     */
    final static ArrayDeque<NamedWeak> pendingSockets = new ArrayDeque<>(5);

    /**
     * Queued objects when they are unreferenced.
     */
    final static ReferenceQueue<Object> pendingQueue = new ReferenceQueue<>();

    // Server to echo a datagram packet
    static class Server implements Runnable {

        MulticastSocket ss;

        Server() throws IOException {
            ss = new MulticastSocket(0);
            System.out.printf("  DatagramServer addr: %s: %d%n",
                    this.getHost(), this.getPort());
            pendingSockets.add(new NamedWeak(ss, pendingQueue, "serverMulticastSocket"));
            extractRefs(ss, "serverMulticastSocket");
        }

        InetAddress getHost() throws UnknownHostException {
            InetAddress localhost = InetAddress.getByName("localhost"); //.getLocalHost();
            return localhost;
        }

        int getPort() {
            return ss.getLocalPort();
        }

        // Receive a byte and send back a byte
        public void run() {
            try {
                byte[] buffer = new byte[50];
                DatagramPacket p = new DatagramPacket(buffer, buffer.length);
                ss.receive(p);
                buffer[0] += 1;
                ss.send(p);         // send back +1

                // do NOT close but 'forget' the socket reference
                ss = null;
            } catch (Exception ioe) {
                ioe.printStackTrace();
            }
        }
    }

    public static void main(String args[]) throws Exception {

        // Create and close a MulticastSocket to warm up the FD count for side effects.
        try (MulticastSocket s = new MulticastSocket(0)) {
            // no-op; close immediately
            s.getLocalPort();   // no-op
        }

        long fdCount0 = getFdCount();
        listProcFD();

        // start a server
        Server svr = new Server();
        Thread thr = new Thread(svr);
        thr.start();

        MulticastSocket client = new MulticastSocket(0);
        client.connect(svr.getHost(), svr.getPort());
        pendingSockets.add(new NamedWeak(client, pendingQueue, "clientMulticastSocket"));
        extractRefs(client, "clientMulticastSocket");

        byte[] msg = new byte[1];
        msg[0] = 1;
        DatagramPacket p = new DatagramPacket(msg, msg.length, svr.getHost(), svr.getPort());
        client.send(p);

        p = new DatagramPacket(msg, msg.length);
        client.receive(p);

        System.out.printf("echo received from: %s%n", p.getSocketAddress());
        if (msg[0] != 2) {
            throw new AssertionError("incorrect data received: expected: 2, actual: " + msg[0]);
        }

        // Do NOT close the MulticastSocket; forget it

        Object ref;
        int loops = 20;
        while (!pendingSockets.isEmpty() && loops-- > 0) {
            ref = pendingQueue.remove(1000L);
            if (ref != null) {
                pendingSockets.remove(ref);
                System.out.printf("  ref freed: %s, remaining: %d%n", ref, pendingSockets.size());
            } else {
                client = null;
                p = null;
                msg = null;
                System.gc();
            }
        }

        thr.join();

        // List the open file descriptors
        long fdCount = getFdCount();
        System.out.printf("Initial fdCount: %d, final fdCount: %d%n", fdCount0, fdCount);
        listProcFD();

        if (loops == 0) {
            throw new AssertionError("Not all references reclaimed");
        }
    }

    // Get the count of open file descriptors, or -1 if not available
    private static long getFdCount() {
        OperatingSystemMXBean mxBean = ManagementFactory.getOperatingSystemMXBean();
        return (mxBean instanceof UnixOperatingSystemMXBean)
                ? ((UnixOperatingSystemMXBean) mxBean).getOpenFileDescriptorCount()
                : -1L;
    }

    // Reflect to find references in the socket implementation that will be gc'd
    private static void extractRefs(MulticastSocket s, String name) {
        try {

            Field socketImplField = DatagramSocket.class.getDeclaredField("impl");
            socketImplField.setAccessible(true);
            Object socketImpl = socketImplField.get(s);

            Field fileDescriptorField = DatagramSocketImpl.class.getDeclaredField("fd");
            fileDescriptorField.setAccessible(true);
            FileDescriptor fileDescriptor = (FileDescriptor) fileDescriptorField.get(socketImpl);
            extractRefs(fileDescriptor, name);

            Class<?> socketImplClass = socketImpl.getClass();
            System.out.printf("socketImplClass: %s%n", socketImplClass);
            if (socketImplClass.getName().equals("java.net.TwoStacksPlainDatagramSocketImpl")) {
                Field fileDescriptor1Field = socketImplClass.getDeclaredField("fd1");
                fileDescriptor1Field.setAccessible(true);
                FileDescriptor fileDescriptor1 = (FileDescriptor) fileDescriptor1Field.get(socketImpl);
                extractRefs(fileDescriptor1, name + "::twoStacksFd1");

            } else {
                System.out.printf("socketImpl class name not matched: %s != %s%n",
                        socketImplClass.getName(), "java.net.TwoStacksPlainDatagramSocketImpl");
            }
        } catch (NoSuchFieldException | IllegalAccessException ex) {
            ex.printStackTrace();
            throw new AssertionError("missing field", ex);
        }
    }

    private static void extractRefs(FileDescriptor fileDescriptor, String name) {
        Object cleanup = null;
        int rawfd = -1;
        try {
            if (fileDescriptor != null) {
                Field fd1Field = FileDescriptor.class.getDeclaredField("fd");
                fd1Field.setAccessible(true);
                rawfd = fd1Field.getInt(fileDescriptor);

                Field cleanupfdField = FileDescriptor.class.getDeclaredField("cleanup");
                cleanupfdField.setAccessible(true);
                cleanup = cleanupfdField.get(fileDescriptor);
                pendingSockets.add(new NamedWeak(fileDescriptor, pendingQueue,
                        name + "::fileDescriptor: " + rawfd));
                pendingSockets.add(new NamedWeak(cleanup, pendingQueue, name + "::fdCleanup: " + rawfd));

            }
        } catch (NoSuchFieldException | IllegalAccessException ex) {
            ex.printStackTrace();
            throw new AssertionError("missing field", ex);
        } finally {
            System.out.print(String.format("  %s:: fd: %s, fd: %d, cleanup: %s%n",
                    name, fileDescriptor, rawfd, cleanup));
        }
    }

    /**
     * Method to list the open file descriptors (if supported by the 'lsof' command).
     */
    static void listProcFD() {
        List<String> lsofDirs = List.of("/usr/bin", "/usr/sbin");
        Optional<Path> lsof = lsofDirs.stream()
                .map(s -> Paths.get(s, "lsof"))
                .filter(f -> Files.isExecutable(f))
                .findFirst();
        lsof.ifPresent(exe -> {
            try {
                System.out.printf("Open File Descriptors:%n");
                long pid = ProcessHandle.current().pid();
                ProcessBuilder pb = new ProcessBuilder(exe.toString(), "-p", Integer.toString((int) pid));
                pb.inheritIO();
                Process p = pb.start();
                p.waitFor(10, TimeUnit.SECONDS);
            } catch (IOException | InterruptedException ie) {
                ie.printStackTrace();
            }
        });
    }


    // Simple class to identify which refs have been queued
    static class NamedWeak extends WeakReference<Object> {
        private final String name;

        NamedWeak(Object o, ReferenceQueue<Object> queue, String name) {
            super(o, queue);
            this.name = name;
        }

        public String toString() {
            return name + "; " + super.toString();
        }
    }
}