org.apache.hadoop.mapreduce.lib.map
Class MultithreadedMapper<K1,V1,K2,V2>

java.lang.Object
  extended by org.apache.hadoop.mapreduce.Mapper<K1,V1,K2,V2>
      extended by org.apache.hadoop.mapreduce.lib.map.MultithreadedMapper<K1,V1,K2,V2>

@InterfaceAudience.Public
@InterfaceStability.Stable
public class MultithreadedMapper<K1,V1,K2,V2>
extends Mapper<K1,V1,K2,V2>

Multithreaded implementation for @link org.apache.hadoop.mapreduce.Mapper.

It can be used instead of the default implementation,


Field Summary
static String MAP_CLASS
           
static String NUM_THREADS
           
 
Constructor Summary
MultithreadedMapper()
           
 
Method Summary
static
<K1,V1,K2,V2>
Class<Mapper<K1,V1,K2,V2>>
getMapperClass(JobContext job)
          Get the application's mapper class.
static int getNumberOfThreads(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
<K1,V1,K2,V2>
void
setMapperClass(Job job, Class<? extends Mapper<K1,V1,K2,V2>> cls)
          Set the application's mapper class.
static void setNumberOfThreads(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

NUM_THREADS

public static String NUM_THREADS

MAP_CLASS

public static String MAP_CLASS
Constructor Detail

MultithreadedMapper

public MultithreadedMapper()
Method Detail

getNumberOfThreads

public static int getNumberOfThreads(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(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 <K1,V1,K2,V2> Class<Mapper<K1,V1,K2,V2>> getMapperClass(JobContext job)
Get the application's mapper class.

Type Parameters:
K1 - the map's input key type
V1 - the map's input value type
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 <K1,V1,K2,V2> void setMapperClass(Job job,
                                                Class<? extends Mapper<K1,V1,K2,V2>> cls)
Set the application's mapper class.

Type Parameters:
K1 - the map input key type
V1 - the map input value type
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 Mapper<K1,V1,K2,V2>
Throws:
IOException
InterruptedException


Copyright © 2012 Apache Software Foundation. All Rights Reserved.