Module org.glassfish.grizzly

Package org.glassfish.grizzly.memory

Class PooledMemoryManager

java.lang.Object

org.glassfish.grizzly.memory.PooledMemoryManager

All Implemented Interfaces:

MemoryManager<Buffer>, WrapperAware, MonitoringAware<MemoryProbe>

public class PooledMemoryManager
extends Object
implements MemoryManager<Buffer>, WrapperAware

A MemoryManager implementation based on a series of shared memory pools. Each pool contains multiple buffers of the fixed length specific for this pool. There are several tuning options for this MemoryManager implementation.

• The base size of the buffer for the 1st pool, every next pool n will have buffer size equal to bufferSize(n-1) * 2^growthFactor
• The number of pools, responsible for allocation of buffers of a pool-specific size
• The buffer size growth factor, that defines 2^x multiplier, used to calculate buffer size for next allocated pool
• The number of pool slices that every pool will stripe allocation requests across
• The percentage of the heap that this manager will use when populating the pools
• The percentage of buffers to be pre-allocated during MemoryManager initialization
• The flag indicating whether direct or heap based Buffers will be allocated

If no explicit configuration is provided, the following defaults will be used:

• Base buffer size: 4 KiB (DEFAULT_BASE_BUFFER_SIZE)
• Number of pools: 3 (DEFAULT_NUMBER_OF_POOLS)
• Growth factor: 2 (DEFAULT_GROWTH_FACTOR), which means the first buffer pool will contains buffer of size 4 KiB, the seconds one buffer of size 16KiB, the third one buffer of size 64KiB
• Number of pool slices: Based on the return value of Runtime.getRuntime().availableProcessors()
• Percentage of heap: 3% (DEFAULT_HEAP_USAGE_PERCENTAGE)
• Percentage of buffers to be pre-allocated: 100% (DEFAULT_PREALLOCATED_BUFFERS_PERCENTAGE)
• Heap based Buffers will be allocated

The main advantage of this manager over HeapMemoryManager or ByteBufferManager is that this implementation doesn't use ThreadLocal pools and as such, doesn't suffer from the memory fragmentation/reallocation cycle that can impact the ThreadLocal versions.

Since:

2.3.11

Field Summary

Fields

Modifier and Type	Field	Description
static final int	DEFAULT_BASE_BUFFER_SIZE
static final int	DEFAULT_GROWTH_FACTOR
static final float	DEFAULT_HEAP_USAGE_PERCENTAGE
static final int	DEFAULT_NUMBER_OF_POOLS
static final float	DEFAULT_PREALLOCATED_BUFFERS_PERCENTAGE
protected final DefaultMonitoringConfig<MemoryProbe>	monitoringConfig	Basic monitoring support.

Fields inherited from interface org.glassfish.grizzly.memory.MemoryManager

DEFAULT_MEMORY_MANAGER

Constructor Summary

Constructors

Constructor	Description
PooledMemoryManager()	Creates a new PooledMemoryManager using the following defaults: 4 KiB base buffer size 3 pools 2 growth factor, which means 1st pool will contain buffers of size 4KiB, the 2nd - 16KiB, the 3rd - 64KiB Number of pool slices based on Runtime.getRuntime().availableProcessors() The initial allocation will use 3% of the heap The percentage of buffers to be pre-allocated during MemoryManager initialization
PooledMemoryManager(boolean isDirect)	Creates a new PooledMemoryManager using the specified parameters for configuration.
PooledMemoryManager(int baseBufferSize, int numberOfPools, int growthFactor, int numberOfPoolSlices, float percentOfHeap, float percentPreallocated, boolean isDirect)	Creates a new PooledMemoryManager using the specified parameters for configuration.

Method Summary

Modifier and Type	Method	Description
Buffer	allocate(int size)	For this implementation, this method simply calls through to allocateAtLeast(int);
Buffer	allocateAtLeast(int size)	Allocates a buffer of at least the size requested.
protected Object	createJmxManagementObject()
MonitoringConfig<MemoryProbe>	getMonitoringConfig()	Return the object associated MonitoringConfig.
Buffer	reallocate(Buffer oldBuffer, int newSize)	Reallocates an existing buffer to at least the specified size.
void	release(Buffer buffer)	Release Buffer.
boolean	willAllocateDirect(int size)	Return true if next MemoryManager.allocate(int) or MemoryManager.allocateAtLeast(int) call, made in the current thread for the given memory size, going to return a Buffer based on direct ByteBuffer, or false otherwise.
Buffer	wrap(byte[] data)	Returns Buffer, which wraps the byte array.
Buffer	wrap(byte[] data, int offset, int length)	Returns Buffer, which wraps the part of byte array with specific offset and length.
Buffer	wrap(String s)	Returns Buffer, which wraps the String.
Buffer	wrap(String s, Charset charset)	Returns Buffer, which wraps the String with the specific Charset.
Buffer	wrap(ByteBuffer byteBuffer)	Returns Buffer, which wraps the ByteBuffer.

Methods inherited from class java.lang.Object

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

Field Details

DEFAULT_BASE_BUFFER_SIZE

public static final int DEFAULT_BASE_BUFFER_SIZE

See Also:

• Constant Field Values

DEFAULT_NUMBER_OF_POOLS

public static final int DEFAULT_NUMBER_OF_POOLS

See Also:

• Constant Field Values

DEFAULT_GROWTH_FACTOR

public static final int DEFAULT_GROWTH_FACTOR

See Also:

• Constant Field Values

DEFAULT_HEAP_USAGE_PERCENTAGE

public static final float DEFAULT_HEAP_USAGE_PERCENTAGE

See Also:

• Constant Field Values

DEFAULT_PREALLOCATED_BUFFERS_PERCENTAGE

public static final float DEFAULT_PREALLOCATED_BUFFERS_PERCENTAGE

See Also:

• Constant Field Values

monitoringConfig

protected final DefaultMonitoringConfig<MemoryProbe> monitoringConfig

Basic monitoring support. Concrete implementations of this class need only to implement the createJmxManagementObject() method to plug into the Grizzly 2.0 JMX framework.

Constructor Details

PooledMemoryManager

public PooledMemoryManager()

Creates a new PooledMemoryManager using the following defaults:

• 4 KiB base buffer size
• 3 pools
• 2 growth factor, which means 1st pool will contain buffers of size 4KiB, the 2nd - 16KiB, the 3rd - 64KiB
• Number of pool slices based on Runtime.getRuntime().availableProcessors()
• The initial allocation will use 3% of the heap
• The percentage of buffers to be pre-allocated during MemoryManager initialization

PooledMemoryManager

public PooledMemoryManager(boolean isDirect)

Creates a new PooledMemoryManager using the specified parameters for configuration.

Parameters:

isDirect - flag, indicating whether direct or heap based Buffers will be allocated

PooledMemoryManager

public PooledMemoryManager(int baseBufferSize,
 int numberOfPools,
 int growthFactor,
 int numberOfPoolSlices,
 float percentOfHeap,
 float percentPreallocated,
 boolean isDirect)

Creates a new PooledMemoryManager using the specified parameters for configuration.

Parameters:

baseBufferSize - the base size of the buffer for the 1st pool, every next pool n will have buffer size equal to bufferSize(n-1) * 2^growthFactor

numberOfPools - the number of pools, responsible for allocation of buffers of a pool-specific size

growthFactor - the buffer size growth factor, that defines 2^x multiplier, used to calculate buffer size for next allocated pool

numberOfPoolSlices - the number of pool slices that every pool will stripe allocation requests across

percentOfHeap - percentage of the heap that will be used when populating the pools

percentPreallocated - percentage of buffers to be pre-allocated during MemoryManager initialization

isDirect - flag, indicating whether direct or heap based Buffers will be allocated

Method Details

allocate

public Buffer allocate(int size)

For this implementation, this method simply calls through to allocateAtLeast(int);

Specified by:

allocate in interface MemoryManager<Buffer>

Parameters:

size - Buffer size to be allocated.

Returns:

allocated Buffer.

allocateAtLeast

public Buffer allocateAtLeast(int size)

Allocates a buffer of at least the size requested.

Keep in mind that the capacity of the buffer may be greater than the allocation request. The limit however, will be set to the specified size. The memory beyond the limit, is available for use.

Specified by:

allocateAtLeast in interface MemoryManager<Buffer>

Parameters:

size - the min Buffer size to be allocated.

Returns:

a buffer with a limit of the specified size.

reallocate

public Buffer reallocate(Buffer oldBuffer,
 int newSize)

Reallocates an existing buffer to at least the specified size.

Specified by:

reallocate in interface MemoryManager<Buffer>

Parameters:

oldBuffer - old Buffer to be reallocated.

newSize - new Buffer required size.

Returns:

potentially a new buffer of at least the specified size.

release

public void release(Buffer buffer)

Release Buffer. Implementation may ignore releasing and let JVM Garbage collector to take care about the Buffer, or return Buffer to pool, in case of more complex MemoryManager implementation.

Specified by:

release in interface MemoryManager<Buffer>

Parameters:

buffer - Buffer to be released.

willAllocateDirect

public boolean willAllocateDirect(int size)

Return true if next MemoryManager.allocate(int) or MemoryManager.allocateAtLeast(int) call, made in the current thread for the given memory size, going to return a Buffer based on direct ByteBuffer, or false otherwise.

Specified by:

willAllocateDirect in interface MemoryManager<Buffer>

Returns:

getMonitoringConfig

public MonitoringConfig<MemoryProbe> getMonitoringConfig()

Return the object associated MonitoringConfig.

Specified by:

getMonitoringConfig in interface MonitoringAware<MemoryProbe>

Returns:

the object associated MonitoringConfig.

wrap

public Buffer wrap(byte[] data)

Description copied from interface: WrapperAware

Returns Buffer, which wraps the byte array.

Specified by:

wrap in interface WrapperAware

Parameters:

data - byte array to wrap

Returns:

Buffer wrapper on top of passed byte array.

wrap

public Buffer wrap(byte[] data,
 int offset,
 int length)

Description copied from interface: WrapperAware

Returns Buffer, which wraps the part of byte array with specific offset and length.

Specified by:

wrap in interface WrapperAware

Parameters:

data - byte array to wrap

offset - byte buffer offset

length - byte buffer length

Returns:

Buffer wrapper on top of passed byte array.

wrap

public Buffer wrap(String s)

Description copied from interface: WrapperAware

Returns Buffer, which wraps the String.

Specified by:

wrap in interface WrapperAware

Parameters:

s - String

Returns:

Buffer wrapper on top of passed String.

wrap

public Buffer wrap(String s,
 Charset charset)

Description copied from interface: WrapperAware

Returns Buffer, which wraps the String with the specific Charset.

Specified by:

wrap in interface WrapperAware

Parameters:

s - String

charset - Charset, which will be used, when converting String to byte array.

Returns:

Buffer wrapper on top of passed String.

wrap

public Buffer wrap(ByteBuffer byteBuffer)

Description copied from interface: WrapperAware

Returns Buffer, which wraps the ByteBuffer.

Specified by:

wrap in interface WrapperAware

Parameters:

byteBuffer - ByteBuffer to wrap

Returns:

Buffer wrapper on top of passed ByteBuffer.

createJmxManagementObject

protected Object createJmxManagementObject()