com.facebook.presto.memory.context

Class MemoryTrackingContext

java.lang.Object

com.facebook.presto.memory.context.MemoryTrackingContext

@ThreadSafe
public final class MemoryTrackingContext
extends Object

This class is used to track memory usage at all levels (operator, driver, pipeline, etc.).

At every level we have three aggregate and three local memory contexts. The local memory contexts track the allocations in the current level while the aggregate memory contexts aggregate the memory allocated by the leaf levels and the current level.

The reason we have local memory contexts at every level is that not all the allocations are done by the leaf levels (e.g., at the pipeline level exchange clients can do system allocations directly, see the ExchangeOperator, another example is the buffers doing system allocations at the task context level, etc.).

As another example, at the pipeline level there will be system allocations initiated by the operator context and there will be system allocations initiated by the exchange clients (local allocations). All these system allocations will be visible in the systemAggregateMemoryContext.

To perform local allocations clients should use localUserMemoryContext()/localSystemMemoryContext() and get a reference to the local memory contexts. Clients can also use updateUserMemory()/tryReserveUserMemory() to allocate memory (non-local allocations), which will be reflected to all ancestors of this context in the hierarchy.

Constructor Summary

Constructors

Constructor and Description
MemoryTrackingContext(AggregatedMemoryContext userAggregateMemoryContext, AggregatedMemoryContext revocableAggregateMemoryContext, AggregatedMemoryContext systemAggregateMemoryContext)

Method Summary

Modifier and Type	Method and Description
AggregatedMemoryContext	aggregateUserMemoryContext()
void	close()
long	getRevocableMemory()
long	getSystemMemory()
long	getUserMemory()
void	initializeLocalMemoryContexts(String allocationTag) This method has to be called to initialize the local memory contexts.
LocalMemoryContext	localRevocableMemoryContext()
LocalMemoryContext	localSystemMemoryContext()
LocalMemoryContext	localUserMemoryContext()
AggregatedMemoryContext	newAggregateSystemMemoryContext()
MemoryTrackingContext	newMemoryTrackingContext()
LocalMemoryContext	newSystemMemoryContext(String allocationTag)
LocalMemoryContext	newUserMemoryContext(String allocationTag)
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

MemoryTrackingContext

public MemoryTrackingContext(AggregatedMemoryContext userAggregateMemoryContext,
                             AggregatedMemoryContext revocableAggregateMemoryContext,
                             AggregatedMemoryContext systemAggregateMemoryContext)

Method Detail

close

public void close()

localUserMemoryContext

public LocalMemoryContext localUserMemoryContext()

localSystemMemoryContext

public LocalMemoryContext localSystemMemoryContext()

localRevocableMemoryContext

public LocalMemoryContext localRevocableMemoryContext()

newUserMemoryContext

public LocalMemoryContext newUserMemoryContext(String allocationTag)

newSystemMemoryContext

public LocalMemoryContext newSystemMemoryContext(String allocationTag)

aggregateUserMemoryContext

public AggregatedMemoryContext aggregateUserMemoryContext()

newAggregateSystemMemoryContext

public AggregatedMemoryContext newAggregateSystemMemoryContext()

getUserMemory

public long getUserMemory()

getRevocableMemory

public long getRevocableMemory()

getSystemMemory

public long getSystemMemory()

newMemoryTrackingContext

public MemoryTrackingContext newMemoryTrackingContext()

initializeLocalMemoryContexts

public void initializeLocalMemoryContexts(String allocationTag)

This method has to be called to initialize the local memory contexts. Otherwise, calls to methods localUserMemoryContext(), localSystemMemoryContext(), etc. will fail.

toString

public String toString()

Overrides:

toString in class Object