1 /*

     2  * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  */

    23 

    24 /* @test

    25  * @bug 8147615

    26  * @summary Test whether an unreferenced FileChannel is actually cleaned

    27  * @requires (os.family == "linux") | (os.family == "mac") | (os.family == "solaris") | (os.family == "aix")

    28  * @modules java.management

    29  * @run main/othervm CleanerTest

    30  */

    31 

    32 import com.sun.management.UnixOperatingSystemMXBean;

    33 import java.lang.management.ManagementFactory;

    34 import java.lang.management.OperatingSystemMXBean;

    35 import java.lang.ref.PhantomReference;

    36 import java.lang.ref.Reference;

    37 import java.lang.ref.ReferenceQueue;

    38 import java.nio.channels.FileChannel;

    39 import java.nio.file.Files;

    40 import java.nio.file.Path;

    41 import java.nio.file.Paths;

    42 import java.nio.file.StandardOpenOption;

    43 

    44 public class CleanerTest {

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

    46         OperatingSystemMXBean mxBean =

    47             ManagementFactory.getOperatingSystemMXBean();

    48         UnixOperatingSystemMXBean unixMxBean = null;

    49         if (mxBean instanceof UnixOperatingSystemMXBean) {

    50             unixMxBean = (UnixOperatingSystemMXBean)mxBean;

    51         } else {

    52             System.out.println("Non-Unix system: skipping test.");

    53             return;

    54         }

    55 

    56         Path path = Paths.get(System.getProperty("test.dir", "."), "junk");

    57         try {

    58             FileChannel fc = FileChannel.open(path, StandardOpenOption.CREATE,

    59                 StandardOpenOption.READ, StandardOpenOption.WRITE);

    60 

    61             ReferenceQueue refQueue = new ReferenceQueue();

    62             Reference fcRef = new PhantomReference(fc, refQueue);

    63 

    64             long fdCount0 = unixMxBean.getOpenFileDescriptorCount();

    65             fc = null;

    66 

    67             // Perform repeated GCs until the reference has been enqueued.

    68             do {

    69                 Thread.sleep(1);

    70                 System.gc();

    71             } while (refQueue.poll() == null);

    72 

    73             // Loop until the open file descriptor count has been decremented.

    74             while (unixMxBean.getOpenFileDescriptorCount() > fdCount0 - 1) {

    75                 Thread.sleep(1);

    76             }

    77 

    78             long fdCount = unixMxBean.getOpenFileDescriptorCount();

    79             if (fdCount != fdCount0 - 1) {

    80                 throw new RuntimeException("FD count expected " +

    81                     (fdCount0 - 1) + "; actual " + fdCount);

    82             }

    83         } finally {

    84             Files.delete(path);

    85         }

    86     }

    87 }