test/java/lang/management/BufferPoolMXBean/Basic.java

*** 20,43 ****
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  /* @test
!  * @bug 6606598
!  * @summary Unit test for java.nio.BufferPoolMXBean
   * @run main/othervm Basic
   */
  
  import java.nio.ByteBuffer;
  import java.nio.MappedByteBuffer;
! import java.nio.BufferPoolMXBean;
  import java.nio.channels.FileChannel;
! import java.io.File;
! import java.io.RandomAccessFile;
  import java.lang.management.ManagementFactory;
  import javax.management.MBeanServer;
  import javax.management.ObjectName;
  import java.util.*;
  
  public class Basic {
  
      // static fields to ensure buffers aren't GC'ed
--- 20,45 ----
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  /* @test
!  * @bug 6606598 7024172
!  * @summary Unit test for java.lang.management.BufferPoolMXBean
   * @run main/othervm Basic
   */
  
  import java.nio.ByteBuffer;
  import java.nio.MappedByteBuffer;
! import java.nio.file.Path;
! import java.nio.file.Files;
! import static java.nio.file.StandardOpenOption.*;
  import java.nio.channels.FileChannel;
! import java.lang.management.BufferPoolMXBean;
  import java.lang.management.ManagementFactory;
  import javax.management.MBeanServer;
  import javax.management.ObjectName;
+ import java.lang.ref.WeakReference;
  import java.util.*;
  
  public class Basic {
  
      // static fields to ensure buffers aren't GC'ed
*** 76,100 ****
              int cap = 1024 + rand.nextInt(4096);
              buffers.add( ByteBuffer.allocateDirect(cap) );
              totalCapacity += cap;
          }
  
!         // map a file
!         File f = File.createTempFile("blah", null);
!         f.deleteOnExit();
!         RandomAccessFile raf = new RandomAccessFile(f, "rw");
!         FileChannel fc = raf.getChannel();
          mbb = fc.map(FileChannel.MapMode.READ_WRITE, 10, 100);
          bufferCount++;
          totalCapacity += mbb.capacity();
  
!         // direct
          List<BufferPoolMXBean> pools =
              ManagementFactory.getPlatformMXBeans(BufferPoolMXBean.class);
          check(pools, bufferCount, totalCapacity);
  
!         // using MBeanServer
          MBeanServer server = ManagementFactory.getPlatformMBeanServer();
          Set<ObjectName> mbeans = server.queryNames(
              new ObjectName("java.nio:type=BufferPool,*"), null);
          pools = new ArrayList<BufferPoolMXBean>();
          for (ObjectName name: mbeans) {
--- 78,102 ----
              int cap = 1024 + rand.nextInt(4096);
              buffers.add( ByteBuffer.allocateDirect(cap) );
              totalCapacity += cap;
          }
  
!         // create a mapped buffer
!         Path tmpfile = Files.createTempFile("blah", null);
!         tmpfile.toFile().deleteOnExit();
!         try (FileChannel fc = FileChannel.open(tmpfile, READ, WRITE)) {
              mbb = fc.map(FileChannel.MapMode.READ_WRITE, 10, 100);
              bufferCount++;
              totalCapacity += mbb.capacity();
+         }
  
!         // use platform MXBeans directly
          List<BufferPoolMXBean> pools =
              ManagementFactory.getPlatformMXBeans(BufferPoolMXBean.class);
          check(pools, bufferCount, totalCapacity);
  
!         // use MBeanServer
          MBeanServer server = ManagementFactory.getPlatformMBeanServer();
          Set<ObjectName> mbeans = server.queryNames(
              new ObjectName("java.nio:type=BufferPool,*"), null);
          pools = new ArrayList<BufferPoolMXBean>();
          for (ObjectName name: mbeans) {
*** 101,107 ****
--- 103,117 ----
              BufferPoolMXBean pool = ManagementFactory
                  .newPlatformMXBeanProxy(server, name.toString(), BufferPoolMXBean.class);
              pools.add(pool);
          }
          check(pools, bufferCount, totalCapacity);
+ 
+         // attempt to unmap mapped buffer
+         WeakReference<MappedByteBuffer> ref = new WeakReference<>(mbb);
+         mbb = null;
+         do {
+             System.gc();
+             Thread.sleep(250);
+         } while (ref.get() != null);
      }
  }