Package org.apache.drill.exec.memory

Class AllocationManager

java.lang.Object

org.apache.drill.exec.memory.AllocationManager

public class AllocationManager
extends Object

Manages the relationship between one or more allocators and a particular UDLE. Ensures that one allocator owns the memory that multiple allocators may be referencing. Manages a BufferLedger between each of its associated allocators. This class is also responsible for managing when memory is allocated and returned to the Netty-based {code PooledByteBufAllocatorL}.

The only reason that this isn't package private is we're forced to put DrillBuf in Netty's package which need access to these objects or methods.

Threading: AllocationManager manages thread-safety internally. Operations within the context of a single BufferLedger are lockless in nature and can be leveraged by multiple threads. Operations that cross the context of two ledgers will acquire a lock on the AllocationManager instance. Important note, there is one AllocationManager per UnsafeDirectLittleEndian buffer allocation. As such, there will be thousands of these in a typical query. The contention of acquiring a lock on AllocationManager should be very low.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
class	AllocationManager.BufferLedger	The reference manager that binds an allocator manager to a particular BaseAllocator.

Method Summary

Modifier and Type	Method	Description
static int	chunkSize()

Methods inherited from class java.lang.Object

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

Method Details

chunkSize

public static int chunkSize()