org.apache.hadoop.mapreduce.lib.map

类 MultithreadedMapper<K1,V1,K2,V2>

java.lang.Object

org.apache.hadoop.mapreduce.Mapper<K1,V1,K2,V2>

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

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,

嵌套类概要

从类继承的嵌套类/接口 org.apache.hadoop.mapreduce.Mapper

Mapper.Context

构造器概要

构造器

构造器和说明
MultithreadedMapper()

方法概要

方法

限定符和类型	方法和说明
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(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.

从类继承的方法 org.apache.hadoop.mapreduce.Mapper

cleanup, map, setup

从类继承的方法 java.lang.Object

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

构造器详细资料

MultithreadedMapper

public MultithreadedMapper()

方法详细资料

getNumberOfThreads

public static int getNumberOfThreads(JobContext job)

The number of threads in the thread pool that will run the map function.

参数:

job - the job

返回:

the number of threads

setNumberOfThreads

public static void setNumberOfThreads(Job job,
                      int threads)

Set the number of threads in the pool for running maps.

参数:

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.

类型参数:

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

参数:

job - the job

返回:

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.

类型参数:

K1 - the map input key type

V1 - the map input value type

K2 - the map output key type

V2 - the map output value type

参数:

job - the job to modify

cls - the class to use as the mapper

run

public void run(Mapper.Context context)
         throws IOException,
                InterruptedException

Run the application's maps using a thread pool.

覆盖:

run 在类中 Mapper<K1,V1,K2,V2>

抛出:

IOException

InterruptedException