org.apache.hadoop.examples

类 SleepJob

java.lang.Object

org.apache.hadoop.conf.Configured

org.apache.hadoop.examples.SleepJob

所有已实现的接口:

Closeable, AutoCloseable, Configurable, JobConfigurable, Mapper<IntWritable,IntWritable,IntWritable,NullWritable>, Partitioner<IntWritable,NullWritable>, Reducer<IntWritable,NullWritable,NullWritable,NullWritable>, Tool

public class SleepJob
extends Configured
implements Tool, Mapper<IntWritable,IntWritable,IntWritable,NullWritable>, Reducer<IntWritable,NullWritable,NullWritable,NullWritable>, Partitioner<IntWritable,NullWritable>

Dummy class for testing MR framefork. Sleeps for a defined period of time in mapper and reducer. Generates fake input for map / reduce jobs. Note that generated number of input pairs is in the order of numMappers * mapSleepTime / 100, so the job uses some disk space.

嵌套类概要

嵌套类

限定符和类型	类和说明
static class	SleepJob.EmptySplit
static class	SleepJob.SleepInputFormat

构造器概要

构造器

构造器和说明
SleepJob()

方法概要

方法

限定符和类型	方法和说明
void	close()
void	configure(JobConf job) Initializes a new instance from a JobConf.
int	getPartition(IntWritable k, NullWritable v, int numPartitions) Get the paritition number for a given key (hence record) given the total number of partitions i.e. number of reduce-tasks for the job.
static void	main(String[] args)
void	map(IntWritable key, IntWritable value, OutputCollector<IntWritable,NullWritable> output, Reporter reporter) Maps a single input key/value pair into an intermediate key/value pair.
void	reduce(IntWritable key, Iterator<NullWritable> values, OutputCollector<NullWritable,NullWritable> output, Reporter reporter) Reduces values for a given key.
int	run(int numMapper, int numReducer, long mapSleepTime, int mapSleepCount, long reduceSleepTime, int reduceSleepCount)
int	run(String[] args) Execute the command with the given arguments.
JobConf	setupJobConf(int numMapper, int numReducer, long mapSleepTime, int mapSleepCount, long reduceSleepTime, int reduceSleepCount)

从类继承的方法 org.apache.hadoop.conf.Configured

getConf, setConf

从类继承的方法 java.lang.Object

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

从接口继承的方法 org.apache.hadoop.conf.Configurable

getConf, setConf

构造器详细资料

SleepJob

public SleepJob()

方法详细资料

getPartition

public int getPartition(IntWritable k,
               NullWritable v,
               int numPartitions)

从接口复制的说明: Partitioner

Get the paritition number for a given key (hence record) given the total number of partitions i.e. number of reduce-tasks for the job.

Typically a hash function on a all or a subset of the key.

指定者:

getPartition 在接口中 Partitioner<IntWritable,NullWritable>

参数:

k - the key to be paritioned.

v - the entry value.

numPartitions - the total number of partitions.

返回:

the partition number for the key.

map

public void map(IntWritable key,
       IntWritable value,
       OutputCollector<IntWritable,NullWritable> output,
       Reporter reporter)
         throws IOException

从接口复制的说明: Mapper

Maps a single input key/value pair into an intermediate key/value pair.

Output pairs need not be of the same types as input pairs. A given input pair may map to zero or many output pairs. Output pairs are collected with calls to OutputCollector.collect(Object,Object).

Applications can use the Reporter provided to report progress or just indicate that they are alive. In scenarios where the application takes an insignificant amount of time to process individual key/value pairs, this is crucial since the framework might assume that the task has timed-out and kill that task. The other way of avoiding this is to set mapred.task.timeout to a high-enough value (or even zero for no time-outs).

指定者:

map 在接口中 Mapper<IntWritable,IntWritable,IntWritable,NullWritable>

参数:

key - the input key.

value - the input value.

output - collects mapped keys and values.

reporter - facility to report progress.

抛出:

IOException

reduce

public void reduce(IntWritable key,
          Iterator<NullWritable> values,
          OutputCollector<NullWritable,NullWritable> output,
          Reporter reporter)
            throws IOException

从接口复制的说明: Reducer

Reduces values for a given key.

The framework calls this method for each <key, (list of values)> pair in the grouped inputs. Output values must be of the same type as input values. Input keys must not be altered. The framework will reuse the key and value objects that are passed into the reduce, therefore the application should clone the objects they want to keep a copy of. In many cases, all values are combined into zero or one value.

Output pairs are collected with calls to OutputCollector.collect(Object,Object).

Applications can use the Reporter provided to report progress or just indicate that they are alive. In scenarios where the application takes an insignificant amount of time to process individual key/value pairs, this is crucial since the framework might assume that the task has timed-out and kill that task. The other way of avoiding this is to set mapred.task.timeout to a high-enough value (or even zero for no time-outs).

指定者:

reduce 在接口中 Reducer<IntWritable,NullWritable,NullWritable,NullWritable>

参数:

key - the key.

values - the list of values to reduce.

output - to collect keys and combined values.

reporter - facility to report progress.

抛出:

IOException

configure

public void configure(JobConf job)

从接口复制的说明: JobConfigurable

Initializes a new instance from a JobConf.

指定者:

configure 在接口中 JobConfigurable

参数:

job - the configuration

close

public void close()
           throws IOException

指定者:

close 在接口中 Closeable

指定者:

close 在接口中 AutoCloseable

抛出:

IOException

main

public static void main(String[] args)
                 throws Exception

抛出:

Exception

run

public int run(int numMapper,
      int numReducer,
      long mapSleepTime,
      int mapSleepCount,
      long reduceSleepTime,
      int reduceSleepCount)
        throws IOException

抛出:

IOException

setupJobConf

public JobConf setupJobConf(int numMapper,
                   int numReducer,
                   long mapSleepTime,
                   int mapSleepCount,
                   long reduceSleepTime,
                   int reduceSleepCount)

run

public int run(String[] args)
        throws Exception

从接口复制的说明: Tool

Execute the command with the given arguments.

指定者:

run 在接口中 Tool

参数:

args - command specific arguments.

返回:

exit code.

抛出:

Exception