Basic.java revision 6073:cea72c2bf071
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 */ 29 30import java.nio.ByteBuffer; 31import java.nio.MappedByteBuffer; 32import java.nio.file.Path; 33import java.nio.file.Files; 34import static java.nio.file.StandardOpenOption.*; 35import java.nio.channels.FileChannel; 36import java.lang.management.BufferPoolMXBean; 37import java.lang.management.ManagementFactory; 38import javax.management.MBeanServer; 39import javax.management.ObjectName; 40import java.lang.ref.WeakReference; 41import java.util.*; 42 43public class Basic { 44 45 // static fields to ensure buffers aren't GC'ed 46 static List<ByteBuffer> buffers; 47 static MappedByteBuffer mbb; 48 49 // check counters 50 static void check(List<BufferPoolMXBean> pools, 51 int minBufferCount, 52 long minTotalCapacity) 53 { 54 int bufferCount = 0; 55 long totalCap = 0; 56 long totalMem = 0; 57 for (BufferPoolMXBean pool: pools) { 58 bufferCount += pool.getCount(); 59 totalCap += pool.getTotalCapacity(); 60 totalMem += pool.getMemoryUsed(); 61 } 62 if (bufferCount < minBufferCount) 63 throw new RuntimeException("Count less than expected"); 64 if (totalMem < minTotalCapacity) 65 throw new RuntimeException("Memory usage less than expected"); 66 if (totalCap < minTotalCapacity) 67 throw new RuntimeException("Total capacity less than expected"); 68 } 69 70 public static void main(String[] args) throws Exception { 71 Random rand = new Random(); 72 73 // allocate a few direct buffers 74 int bufferCount = 5 + rand.nextInt(20); 75 buffers = new ArrayList<ByteBuffer>(bufferCount); 76 long totalCapacity = 0L; 77 for (int i=0; i<bufferCount; i++) { 78 int cap = 1024 + rand.nextInt(4096); 79 buffers.add( ByteBuffer.allocateDirect(cap) ); 80 totalCapacity += cap; 81 } 82 83 // create a mapped buffer 84 Path tmpfile = Files.createTempFile("blah", null); 85 tmpfile.toFile().deleteOnExit(); 86 try (FileChannel fc = FileChannel.open(tmpfile, READ, WRITE)) { 87 mbb = fc.map(FileChannel.MapMode.READ_WRITE, 10, 100); 88 bufferCount++; 89 totalCapacity += mbb.capacity(); 90 } 91 92 // use platform MXBeans directly 93 List<BufferPoolMXBean> pools = 94 ManagementFactory.getPlatformMXBeans(BufferPoolMXBean.class); 95 check(pools, bufferCount, totalCapacity); 96 97 // use MBeanServer 98 MBeanServer server = ManagementFactory.getPlatformMBeanServer(); 99 Set<ObjectName> mbeans = server.queryNames( 100 new ObjectName("java.nio:type=BufferPool,*"), null); 101 pools = new ArrayList<BufferPoolMXBean>(); 102 for (ObjectName name: mbeans) { 103 BufferPoolMXBean pool = ManagementFactory 104 .newPlatformMXBeanProxy(server, name.toString(), BufferPoolMXBean.class); 105 pools.add(pool); 106 } 107 check(pools, bufferCount, totalCapacity); 108 109 // attempt to unmap mapped buffer 110 WeakReference<MappedByteBuffer> ref = new WeakReference<>(mbb); 111 mbb = null; 112 do { 113 System.gc(); 114 Thread.sleep(250); 115 } while (ref.get() != null); 116 } 117} 118