org.apache.hadoop.hbase.util

Class DirectMemoryUtils

java.lang.Object

org.apache.hadoop.hbase.util.DirectMemoryUtils

@InterfaceAudience.Private
 @InterfaceStability.Evolving
public class DirectMemoryUtils
extends Object

Utilities for interacting with and monitoring DirectByteBuffer allocations.

Constructor Summary

Constructors

Constructor and Description
DirectMemoryUtils()

Method Summary

Modifier and Type	Method and Description
static void	destroyDirectByteBuffer(ByteBuffer toBeDestroyed) DirectByteBuffers are garbage collected by using a phantom reference and a reference queue.
static long	getDirectMemorySize() Returns the direct memory limit of the current progress
static long	getDirectMemoryUsage() Returns the current amount of direct memory used.
static long	getNettyDirectMemoryUsage() Returns the current amount of direct memory used by netty module.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

DirectMemoryUtils

public DirectMemoryUtils()

Method Detail

getDirectMemorySize

public static long getDirectMemorySize()

Returns the direct memory limit of the current progress

getDirectMemoryUsage

public static long getDirectMemoryUsage()

Returns the current amount of direct memory used.

getNettyDirectMemoryUsage

public static long getNettyDirectMemoryUsage()

Returns the current amount of direct memory used by netty module.

destroyDirectByteBuffer

public static void destroyDirectByteBuffer(ByteBuffer toBeDestroyed)
                                    throws IllegalArgumentException,
                                           IllegalAccessException,
                                           InvocationTargetException,
                                           SecurityException,
                                           NoSuchMethodException

DirectByteBuffers are garbage collected by using a phantom reference and a reference queue. Every once a while, the JVM checks the reference queue and cleans the DirectByteBuffers. However, as this doesn't happen immediately after discarding all references to a DirectByteBuffer, it's easy to OutOfMemoryError yourself using DirectByteBuffers. This function explicitly calls the Cleaner method of a DirectByteBuffer. The DirectByteBuffer that will be "cleaned". Utilizes reflection.

Throws:

IllegalArgumentException

IllegalAccessException

InvocationTargetException

SecurityException

NoSuchMethodException