MultithreadedTableMapper (Apache HBase 1.2.12 API)

java.lang.Object
- org.apache.hadoop.mapreduce.Mapper<ImmutableBytesWritable,Result,KEYOUT,VALUEOUT>
- - org.apache.hadoop.hbase.mapreduce.TableMapper<K2,V2>
  - - org.apache.hadoop.hbase.mapreduce.MultithreadedTableMapper<K2,V2>

```
public class MultithreadedTableMapper<K2,V2>
extends TableMapper<K2,V2>
```
Multithreaded implementation for @link org.apache.hbase.mapreduce.TableMapper
It can be used instead when the Map operation is not CPU bound in order to improve throughput.
Mapper implementations using this MapRunnable must be thread-safe.
The Map-Reduce job has to be configured with the mapper to use via setMapperClass(org.apache.hadoop.mapreduce.Job, java.lang.Class<? extends org.apache.hadoop.mapreduce.Mapper<org.apache.hadoop.hbase.io.ImmutableBytesWritable, org.apache.hadoop.hbase.client.Result, K2, V2>>) and the number of thread the thread-pool can use with the getNumberOfThreads(org.apache.hadoop.mapreduce.JobContext) method. The default value is 10 threads.

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`private class`	`MultithreadedTableMapper.MapRunner`
`private class`	`MultithreadedTableMapper.SubMapRecordReader`
`private class`	`MultithreadedTableMapper.SubMapRecordWriter`
`private class`	`MultithreadedTableMapper.SubMapStatusReporter`

Nested classes/interfaces inherited from class org.apache.hadoop.mapreduce.Mapper
org.apache.hadoop.mapreduce.Mapper.Context

Field Summary

Fields
Modifier and Type	Field and Description
`private ExecutorService`	`executor`
`private static org.apache.commons.logging.Log`	`LOG`
`private Class<? extends org.apache.hadoop.mapreduce.Mapper<ImmutableBytesWritable,Result,K2,V2>>`	`mapClass`
`static String`	`MAPPER_CLASS`
`static String`	`NUMBER_OF_THREADS`
`private org.apache.hadoop.mapreduce.Mapper.Context`	`outer`

Constructor Summary

Constructors
Constructor and Description

MultithreadedTableMapper()

Constructors
Constructor and Description
`MultithreadedTableMapper()`

Method Summary

Methods
Modifier and Type	Method and Description
`static <K2,V2> Class<org.apache.hadoop.mapreduce.Mapper<ImmutableBytesWritable,Result,K2,V2>>`	`getMapperClass(org.apache.hadoop.mapreduce.JobContext job)` Get the application's mapper class.
`static int`	`getNumberOfThreads(org.apache.hadoop.mapreduce.JobContext job)` The number of threads in the thread pool that will run the map function.
`void`	`run(org.apache.hadoop.mapreduce.Mapper.Context context)` Run the application's maps using a thread pool.
`static <K2,V2> void`	`setMapperClass(org.apache.hadoop.mapreduce.Job job, Class<? extends org.apache.hadoop.mapreduce.Mapper<ImmutableBytesWritable,Result,K2,V2>> cls)` Set the application's mapper class.
`static void`	`setNumberOfThreads(org.apache.hadoop.mapreduce.Job job, int threads)` Set the number of threads in the pool for running maps.

Methods inherited from class org.apache.hadoop.mapreduce.Mapper
cleanup, map, setup

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

mapClass

private Class<? extends org.apache.hadoop.mapreduce.Mapper<ImmutableBytesWritable,Result,K2,V2>> mapClass

outer

private org.apache.hadoop.mapreduce.Mapper.Context outer

executor
```
private ExecutorService executor
```

NUMBER_OF_THREADS

public static final String NUMBER_OF_THREADS

See Also:: Constant Field Values

MAPPER_CLASS

public static final String MAPPER_CLASS

See Also:: Constant Field Values

Constructor Detail
- MultithreadedTableMapper
```
public MultithreadedTableMapper()
```

Method Detail
- getNumberOfThreads
```
public static int getNumberOfThreads(org.apache.hadoop.mapreduce.JobContext job)
```
  The number of threads in the thread pool that will run the map function.
  
  Parameters:
  job - the job
  
  Returns:
  the number of threads
- setNumberOfThreads
```
public static void setNumberOfThreads(org.apache.hadoop.mapreduce.Job job,
                      int threads)
```
  Set the number of threads in the pool for running maps.
  
  Parameters:
  job - the job to modify
  threads - the new number of threads
- getMapperClass
```
public static <K2,V2> Class<org.apache.hadoop.mapreduce.Mapper<ImmutableBytesWritable,Result,K2,V2>> getMapperClass(org.apache.hadoop.mapreduce.JobContext job)
```
  Get the application's mapper class.
  
  Type Parameters:
  K2 - the map's output key type
  V2 - the map's output value type
  Parameters:
  job - the job
  
  Returns:
  the mapper class to run
- setMapperClass
```
public static <K2,V2> void setMapperClass(org.apache.hadoop.mapreduce.Job job,
                          Class<? extends org.apache.hadoop.mapreduce.Mapper<ImmutableBytesWritable,Result,K2,V2>> cls)
```
  Set the application's mapper class.
  
  Type Parameters:
  K2 - the map output key type
  V2 - the map output value type
  Parameters:
  job - the job to modify
  cls - the class to use as the mapper
- run
```
public void run(org.apache.hadoop.mapreduce.Mapper.Context context)
         throws IOException,
                InterruptedException
```
  Run the application's maps using a thread pool.
  
  Overrides:
  
  run in class org.apache.hadoop.mapreduce.Mapper<ImmutableBytesWritable,Result,K2,V2>
  
  Throws:
  
  IOException
  
  InterruptedException

Class MultithreadedTableMapper<K2,V2>

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.hadoop.mapreduce.Mapper

Field Summary

Constructor Summary

Method Summary

Methods inherited from class org.apache.hadoop.mapreduce.Mapper

Methods inherited from class java.lang.Object

Field Detail

LOG

mapClass

outer

executor

NUMBER_OF_THREADS

MAPPER_CLASS

Constructor Detail

MultithreadedTableMapper

Method Detail

getNumberOfThreads

setNumberOfThreads

getMapperClass

setMapperClass

run