org.apache.flink.runtime.memorymanager

Class DefaultMemoryManager

java.lang.Object

org.apache.flink.runtime.memorymanager.DefaultMemoryManager

All Implemented Interfaces:

MemoryManager

public class DefaultMemoryManager
extends Object
implements MemoryManager

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_PAGE_SIZE The default memory page size.
static int	MIN_PAGE_SIZE The minimal memory page size.

Constructor Summary

Constructors

Constructor and Description
DefaultMemoryManager(long memorySize, int numberOfSlots) Creates a memory manager with the given capacity, using the default page size.
DefaultMemoryManager(long memorySize, int numberOfSlots, int pageSize) Creates a memory manager with the given capacity and given page size.

Method Summary

Methods

Modifier and Type	Method and Description
List<MemorySegment>	allocatePages(AbstractInvokable owner, int numPages)
void	allocatePages(AbstractInvokable owner, List<MemorySegment> target, int numPages)
long	computeMemorySize(double fraction) Computes the memory size of the fraction per slot.
int	computeNumberOfPages(double fraction) Computes to how many pages the given number of bytes corresponds.
long	getMemorySize() Returns the total size of memory.
int	getPageSize() Gets the size of the pages handled by the memory manager.
<T extends MemorySegment> void	release(Collection<T> segments) Tries to release the memory for the specified collection of segments.
void	release(MemorySegment segment) Tries to release the memory for the specified segment.
void	releaseAll(AbstractInvokable owner) Releases all memory segments for the given task.
long	roundDownToPageSizeMultiple(long numBytes) Rounds the given value down to a multiple of the memory manager's page size.
void	shutdown() Shuts the memory manager down, trying to release all the memory it managed.
boolean	verifyEmpty() Checks if the memory manager all memory available and the descriptors of the free segments describe a contiguous memory layout.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_PAGE_SIZE

public static final int DEFAULT_PAGE_SIZE

The default memory page size. Currently set to 32 KiBytes.

See Also:

Constant Field Values

MIN_PAGE_SIZE

public static final int MIN_PAGE_SIZE

The minimal memory page size. Currently set to 4 KiBytes.

See Also:

Constant Field Values

Constructor Detail

DefaultMemoryManager

public DefaultMemoryManager(long memorySize,
                    int numberOfSlots)

Creates a memory manager with the given capacity, using the default page size.

Parameters:

memorySize - The total size of the memory to be managed by this memory manager.

DefaultMemoryManager

public DefaultMemoryManager(long memorySize,
                    int numberOfSlots,
                    int pageSize)

Creates a memory manager with the given capacity and given page size.

Parameters:

memorySize - The total size of the memory to be managed by this memory manager.

pageSize - The size of the pages handed out by the memory manager.

Method Detail

shutdown

public void shutdown()

Description copied from interface: MemoryManager

Shuts the memory manager down, trying to release all the memory it managed. Depending on implementation details, the memory does not necessarily become reclaimable by the garbage collector, because there might still be references to allocated segments in the code that allocated them from the memory manager.

Specified by:

shutdown in interface MemoryManager

verifyEmpty

public boolean verifyEmpty()

Description copied from interface: MemoryManager

Checks if the memory manager all memory available and the descriptors of the free segments describe a contiguous memory layout.

Specified by:

verifyEmpty in interface MemoryManager

Returns:

True, if the memory manager is empty and valid, false if it is not empty or corrupted.

allocatePages

public List<MemorySegment> allocatePages(AbstractInvokable owner,
                                int numPages)
                                  throws MemoryAllocationException

Specified by:

allocatePages in interface MemoryManager

Throws:

MemoryAllocationException

allocatePages

public void allocatePages(AbstractInvokable owner,
                 List<MemorySegment> target,
                 int numPages)
                   throws MemoryAllocationException

Specified by:

allocatePages in interface MemoryManager

Throws:

MemoryAllocationException

release

public void release(MemorySegment segment)

Description copied from interface: MemoryManager

Tries to release the memory for the specified segment. If the segment has already been released or is null, the request is simply ignored. If the segment is not from the expected MemorySegment implementation type, an IllegalArgumentException is thrown.

Specified by:

release in interface MemoryManager

Parameters:

segment - The segment to be released.

release

public <T extends MemorySegment> void release(Collection<T> segments)

Description copied from interface: MemoryManager

Tries to release the memory for the specified collection of segments.

Specified by:

release in interface MemoryManager

Type Parameters:

T - The type of memory segment.

Parameters:

segments - The segments to be released.

releaseAll

public void releaseAll(AbstractInvokable owner)

Description copied from interface: MemoryManager

Releases all memory segments for the given task.

Specified by:

releaseAll in interface MemoryManager

Parameters:

owner - The task whose memory segments are to be released.

getPageSize

public int getPageSize()

Description copied from interface: MemoryManager

Gets the size of the pages handled by the memory manager.

Specified by:

getPageSize in interface MemoryManager

Returns:

The size of the pages handled by the memory manager.

getMemorySize

public long getMemorySize()

Description copied from interface: MemoryManager

Returns the total size of memory.

Specified by:

getMemorySize in interface MemoryManager

Returns:

The total size of memory.

computeNumberOfPages

public int computeNumberOfPages(double fraction)

Description copied from interface: MemoryManager

Computes to how many pages the given number of bytes corresponds. If the given number of bytes is not an exact multiple of a page size, the result is rounded down, such that a portion of the memory (smaller than the page size) is not included.

Specified by:

computeNumberOfPages in interface MemoryManager

Parameters:

fraction - the fraction of the total memory per slot

Returns:

The number of pages to which

computeMemorySize

public long computeMemorySize(double fraction)

Description copied from interface: MemoryManager

Computes the memory size of the fraction per slot.

Specified by:

computeMemorySize in interface MemoryManager

Parameters:

fraction - The fraction of the memory of the task slot.

Returns:

The number of pages corresponding to the memory fraction.

roundDownToPageSizeMultiple

public long roundDownToPageSizeMultiple(long numBytes)

Description copied from interface: MemoryManager

Rounds the given value down to a multiple of the memory manager's page size.

Specified by:

roundDownToPageSizeMultiple in interface MemoryManager

Returns:

The given value, rounded down to a multiple of the page size.