MemStoreChunkPool (Apache HBase 1.2.12 API)

java.lang.Object
- org.apache.hadoop.hbase.regionserver.MemStoreChunkPool

```
@InterfaceAudience.Private
public class MemStoreChunkPool
extends Object
```
A pool of HeapMemStoreLAB.Chunk instances. MemStoreChunkPool caches a number of retired chunks for reusing, it could decrease allocating bytes when writing, thereby optimizing the garbage collection on JVM. The pool instance is globally unique and could be obtained through getPool(Configuration) getChunk() is called when MemStoreLAB allocating bytes, and putbackChunks(BlockingQueue) is called when MemStore clearing snapshot for flush

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

private static class MemStoreChunkPool.StatisticsThread

Nested Classes
Modifier and Type	Class and Description
`private static class`	`MemStoreChunkPool.StatisticsThread`

Field Summary

Fields
Modifier and Type	Field and Description
`(package private) static String`	`CHUNK_POOL_INITIALSIZE_KEY`
`(package private) static String`	`CHUNK_POOL_MAXSIZE_KEY`
`(package private) static boolean`	`chunkPoolDisabled` Boolean whether we have disabled the memstore chunk pool entirely.
`private int`	`chunkSize`
`private AtomicLong`	`createdChunkCount`
`private static MemStoreChunkPool`	`GLOBAL_INSTANCE`
`private static org.apache.commons.logging.Log`	`LOG`
`private int`	`maxCount`
`(package private) static float`	`POOL_INITIAL_SIZE_DEFAULT`
`(package private) static float`	`POOL_MAX_SIZE_DEFAULT`
`private BlockingQueue<HeapMemStoreLAB.Chunk>`	`reclaimedChunks`
`private AtomicLong`	`reusedChunkCount`
`private ScheduledExecutorService`	`scheduleThreadPool` Statistics thread schedule pool
`private static int`	`statThreadPeriod` Statistics thread

Constructor Summary

Constructors
Constructor and Description
`MemStoreChunkPool(org.apache.hadoop.conf.Configuration conf, int chunkSize, int maxCount, int initialCount)`

Method Summary

Methods
Modifier and Type	Method and Description
`(package private) void`	`clearChunks()`
`(package private) static void`	`clearDisableFlag()`
`(package private) HeapMemStoreLAB.Chunk`	`getChunk()` Poll a chunk from the pool, reset it if not null, else create a new chunk to return
`(package private) int`	`getMaxCount()`
`(package private) static MemStoreChunkPool`	`getPool(org.apache.hadoop.conf.Configuration conf)`
`(package private) int`	`getPoolSize()`
`private void`	`logStats()`
`(package private) void`	`putbackChunk(HeapMemStoreLAB.Chunk chunk)` Add the chunk to the pool, if the pool has achieved the max size, it will skip it
`(package private) void`	`putbackChunks(BlockingQueue<HeapMemStoreLAB.Chunk> chunks)` Add the chunks to the pool, when the pool achieves the max size, it will skip the remaining chunks

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LOG

private static final org.apache.commons.logging.Log LOG

CHUNK_POOL_MAXSIZE_KEY
```
static final String CHUNK_POOL_MAXSIZE_KEY
```
See Also:
Constant Field Values

CHUNK_POOL_INITIALSIZE_KEY
```
static final String CHUNK_POOL_INITIALSIZE_KEY
```
See Also:
Constant Field Values

POOL_MAX_SIZE_DEFAULT
```
static final float POOL_MAX_SIZE_DEFAULT
```
See Also:
Constant Field Values

POOL_INITIAL_SIZE_DEFAULT
```
static final float POOL_INITIAL_SIZE_DEFAULT
```
See Also:
Constant Field Values

GLOBAL_INSTANCE

private static MemStoreChunkPool GLOBAL_INSTANCE

chunkPoolDisabled
```
static boolean chunkPoolDisabled
```
Boolean whether we have disabled the memstore chunk pool entirely.

maxCount
```
private final int maxCount
```

reclaimedChunks

private final BlockingQueue<HeapMemStoreLAB.Chunk> reclaimedChunks

chunkSize
```
private final int chunkSize
```

scheduleThreadPool

private final ScheduledExecutorService scheduleThreadPool

Statistics thread schedule pool

statThreadPeriod
```
private static final int statThreadPeriod
```
Statistics thread

See Also:
Constant Field Values

createdChunkCount
```
private AtomicLong createdChunkCount
```

reusedChunkCount
```
private AtomicLong reusedChunkCount
```

Constructor Detail

MemStoreChunkPool

MemStoreChunkPool(org.apache.hadoop.conf.Configuration conf,
                 int chunkSize,
                 int maxCount,
                 int initialCount)

Method Detail
- getChunk
```
HeapMemStoreLAB.Chunk getChunk()
```
  Poll a chunk from the pool, reset it if not null, else create a new chunk to return
  
  Returns:
  a chunk
- putbackChunks
```
void putbackChunks(BlockingQueue<HeapMemStoreLAB.Chunk> chunks)
```
  Add the chunks to the pool, when the pool achieves the max size, it will skip the remaining chunks
  
  Parameters:
  chunks -
- putbackChunk
```
void putbackChunk(HeapMemStoreLAB.Chunk chunk)
```
  Add the chunk to the pool, if the pool has achieved the max size, it will skip it
  
  Parameters:
  chunk -
- getPoolSize
```
int getPoolSize()
```
- clearChunks
```
void clearChunks()
```
- logStats
```
private void logStats()
```
- getPool
```
static MemStoreChunkPool getPool(org.apache.hadoop.conf.Configuration conf)
```
  Parameters:
  conf -
  
  Returns:
  the global MemStoreChunkPool instance
- getMaxCount
```
int getMaxCount()
```
- clearDisableFlag
```
static void clearDisableFlag()
```

Class MemStoreChunkPool

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

LOG

CHUNK_POOL_MAXSIZE_KEY

CHUNK_POOL_INITIALSIZE_KEY

POOL_MAX_SIZE_DEFAULT

POOL_INITIAL_SIZE_DEFAULT

GLOBAL_INSTANCE

chunkPoolDisabled

maxCount

reclaimedChunks

chunkSize

scheduleThreadPool

statThreadPeriod

createdChunkCount

reusedChunkCount

Constructor Detail

MemStoreChunkPool

Method Detail

getChunk

putbackChunks

putbackChunk

getPoolSize

clearChunks

logStats

getPool

getMaxCount

clearDisableFlag