Package ai.rapids.cudf

Class MemoryCleaner

java.lang.Object

ai.rapids.cudf.MemoryCleaner

public final class MemoryCleaner
extends Object

ColumnVectors may store data off heap, and because of complicated processing the life time of an individual vector can vary a lot. Typically a java finalizer could be used for this but they can cause a number of performance issues related to gc, and in some cases may effectively leak resources if the heap is large and GC's end up being delayed.

To address these issues the primary way to releasing the resources of a ColumnVector that is stored off of the java heap should be through reference counting. Because memory leaks are really bad for long lived daemons this is intended to be a backup.

When a ColumnVector first allocates off heap resources it should register itself with this along with a Cleaner instance. The Cleaner instance should have no direct links to the ColumnVector that would prevent the ColumnVector from being garbage collected. This will use WeakReferences internally to know when the resources have been leaked. A ColumnVector may keep a reference to the Cleaner instance and either update it as new resources are allocated or use it to release the resources it is holding. Once the ColumnVector's reference count reaches 0 and the resources are released. At some point later the Cleaner itself will be released.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	MemoryCleaner.Cleaner	API that can be used to clean up the resources for a vector, even if there was a leak

Constructor Summary

Constructors

Constructor	Description
MemoryCleaner()

Method Summary

Modifier and Type	Method	Description
static boolean	configuredDefaultShutdownHook()	Check if configured the shutdown hook which checks leaks at shutdown time.
static void	register(CompiledExpression expr, MemoryCleaner.Cleaner cleaner)
static Runnable	removeDefaultShutdownHook()	De-register the default shutdown hook from Java default Runtime, then return the corresponding shutdown runnable.

Methods inherited from class java.lang.Object

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

Constructor Details

MemoryCleaner

public MemoryCleaner()

Method Details

configuredDefaultShutdownHook

public static boolean configuredDefaultShutdownHook()

Check if configured the shutdown hook which checks leaks at shutdown time.

Returns:

true if configured, false otherwise.

removeDefaultShutdownHook

public static Runnable removeDefaultShutdownHook()

De-register the default shutdown hook from Java default Runtime, then return the corresponding shutdown runnable. If you want to register the default shutdown runnable in a custom shutdown hook manager instead of Java default Runtime, should first remove it using this method and then add it

Returns:

the default shutdown runnable

register

public static void register(CompiledExpression expr,
 MemoryCleaner.Cleaner cleaner)