1 /* 2 * Copyright (c) 2007, 2011, 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 6606598 7024172 26 * @summary Unit test for java.lang.management.BufferPoolMXBean 27 * @run main/othervm Basic 28 * @key randomness 29 */ 30 31 import java.nio.ByteBuffer; 32 import java.nio.MappedByteBuffer; 33 import java.nio.file.Path; 34 import java.nio.file.Files; 35 import static java.nio.file.StandardOpenOption.*; 36 import java.nio.channels.FileChannel; 37 import java.lang.management.BufferPoolMXBean; 38 import java.lang.management.ManagementFactory; 39 import javax.management.MBeanServer; 40 import javax.management.ObjectName; 41 import java.lang.ref.WeakReference; 42 import java.util.*; 43 44 public class Basic { 45 46 // static fields to ensure buffers aren't GC'ed 47 static List<ByteBuffer> buffers; 48 static MappedByteBuffer mbb; 49 50 // check counters 51 static void check(List<BufferPoolMXBean> pools, 52 int minBufferCount, 53 long minTotalCapacity) 54 { 55 int bufferCount = 0; 56 long totalCap = 0; 57 long totalMem = 0; 58 for (BufferPoolMXBean pool: pools) { 59 bufferCount += pool.getCount(); 60 totalCap += pool.getTotalCapacity(); 61 totalMem += pool.getMemoryUsed(); 62 } 63 if (bufferCount < minBufferCount) 64 throw new RuntimeException("Count less than expected"); 65 if (totalMem < minTotalCapacity) 66 throw new RuntimeException("Memory usage less than expected"); 67 if (totalCap < minTotalCapacity) 68 throw new RuntimeException("Total capacity less than expected"); 69 } 70 71 public static void main(String[] args) throws Exception { 72 Random rand = new Random(); 73 74 // allocate a few direct buffers 75 int bufferCount = 5 + rand.nextInt(20); 76 buffers = new ArrayList<ByteBuffer>(bufferCount); 77 long totalCapacity = 0L; 78 for (int i=0; i<bufferCount; i++) { 79 int cap = 1024 + rand.nextInt(4096); 80 buffers.add( ByteBuffer.allocateDirect(cap) ); 81 totalCapacity += cap; 82 } 83 84 // create a mapped buffer 85 Path tmpfile = Files.createTempFile("blah", null); 86 tmpfile.toFile().deleteOnExit(); 87 try (FileChannel fc = FileChannel.open(tmpfile, READ, WRITE)) { 88 mbb = fc.map(FileChannel.MapMode.READ_WRITE, 10, 100); 89 bufferCount++; 90 totalCapacity += mbb.capacity(); 91 } 92 93 // use platform MXBeans directly 94 List<BufferPoolMXBean> pools = 95 ManagementFactory.getPlatformMXBeans(BufferPoolMXBean.class); 96 check(pools, bufferCount, totalCapacity); 97 98 // use MBeanServer 99 MBeanServer server = ManagementFactory.getPlatformMBeanServer(); 100 Set<ObjectName> mbeans = server.queryNames( 101 new ObjectName("java.nio:type=BufferPool,*"), null); 102 pools = new ArrayList<BufferPoolMXBean>(); 103 for (ObjectName name: mbeans) { 104 BufferPoolMXBean pool = ManagementFactory 105 .newPlatformMXBeanProxy(server, name.toString(), BufferPoolMXBean.class); 106 pools.add(pool); 107 } 108 check(pools, bufferCount, totalCapacity); 109 110 // attempt to unmap mapped buffer 111 WeakReference<MappedByteBuffer> ref = new WeakReference<>(mbb); 112 mbb = null; 113 do { 114 System.gc(); 115 Thread.sleep(250); 116 } while (ref.get() != null); 117 } 118 }