org.apache.drill.exec.memory

Class Accountant

java.lang.Object

org.apache.drill.exec.memory.Accountant

All Implemented Interfaces:

AutoCloseable

Direct Known Subclasses:

BaseAllocator

@ThreadSafe
public class Accountant
extends Object
implements AutoCloseable

Provides a concurrent way to manage account for memory usage without locking. Used as basis for Allocators. All operations are threadsafe (except for close).

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Accountant.AllocationOutcome Describes the type of outcome that occurred when trying to account for allocation of memory.

Field Summary

Fields

Modifier and Type	Field and Description
static boolean	ALLOW_LENIENCY
static String	ALLOW_LENIENT_ALLOCATION
static int	GRACE_MARGIN
static int	MAX_GRACE
protected Accountant	parent The parent allocator
protected long	reservation The amount of memory reserved for this allocator.

Constructor Summary

Constructors

Constructor and Description
Accountant(Accountant parent, long reservation, long maxAllocation)

Method Summary

Modifier and Type	Method and Description
void	close() Close this Accountant.
void	forceLenient() Force lenient allocation.
long	getAllocatedMemory() Return the current amount of allocated memory that this Accountant is managing accounting for.
long	getLimit() Return the current limit of this Accountant.
long	getPeakMemoryAllocation() The peak memory allocated by this Accountant.
boolean	isOverLimit()
void	releaseBytes(long size)
boolean	setLenient() Request lenient allocations: allows exceeding the allocation limit by the configured grace amount.
void	setLimit(long newLimit) Set the maximum amount of memory that can be allocated in the this Accountant before failing an allocation.

Methods inherited from class java.lang.Object

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

Field Detail

ALLOW_LENIENT_ALLOCATION

public static final String ALLOW_LENIENT_ALLOCATION

See Also:

Constant Field Values

GRACE_MARGIN

public static final int GRACE_MARGIN

See Also:

Constant Field Values

MAX_GRACE

public static final int MAX_GRACE

See Also:

Constant Field Values

ALLOW_LENIENCY

public static final boolean ALLOW_LENIENCY

parent

protected final Accountant parent

The parent allocator

reservation

protected final long reservation

The amount of memory reserved for this allocator. Releases below this amount of memory will not be returned to the parent Accountant until this Accountant is closed.

Constructor Detail

Accountant

public Accountant(Accountant parent,
                  long reservation,
                  long maxAllocation)

Method Detail

setLenient

public boolean setLenient()

Request lenient allocations: allows exceeding the allocation limit by the configured grace amount. The request is granted only if strict limits are not required.

Returns:

true if the leniency was granted, false if the current execution mode, or system property, disallows leniency

forceLenient

public void forceLenient()

Force lenient allocation. Used for testing to avoid the need to muck with global settings (assertions or system properties.) Do not use in production code!

releaseBytes

public void releaseBytes(long size)

setLimit

public void setLimit(long newLimit)

Set the maximum amount of memory that can be allocated in the this Accountant before failing an allocation.

Parameters:

newLimit - The limit in bytes.

isOverLimit

public boolean isOverLimit()

close

public void close()

Close this Accountant. This will release any reservation bytes back to a parent Accountant.

Specified by:

close in interface AutoCloseable

getLimit

public long getLimit()

Return the current limit of this Accountant.

Returns:

Limit in bytes.

getAllocatedMemory

public long getAllocatedMemory()

Return the current amount of allocated memory that this Accountant is managing accounting for. Note this does not include reservation memory that hasn't been allocated.

Returns:

Currently allocate memory in bytes.

getPeakMemoryAllocation

public long getPeakMemoryAllocation()

The peak memory allocated by this Accountant.

Returns:

The peak allocated memory in bytes.