org.apache.hadoop.mapred

Class MapTask

java.lang.Object

org.apache.hadoop.mapred.Task

org.apache.hadoop.mapred.MapTask

All Implemented Interfaces:

org.apache.hadoop.conf.Configurable, org.apache.hadoop.io.Writable

@InterfaceAudience.LimitedPrivate(value="MapReduce")
@InterfaceStability.Unstable
public class MapTask
extends Task

A Map task.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	MapTask.MapOutputBuffer<K,V>

Nested classes/interfaces inherited from class org.apache.hadoop.mapred.Task

Task.CombineOutputCollector<K,V>, Task.CombinerRunner<K,V>, Task.CombineValuesIterator<KEY,VALUE>, Task.Counter, Task.NewCombinerRunner<K,V>, Task.OldCombinerRunner<K,V>, Task.TaskReporter

Field Summary

Fields

Modifier and Type	Field and Description
static int	MAP_OUTPUT_INDEX_RECORD_LENGTH The size of each record in the index file for the map-outputs.

Fields inherited from class org.apache.hadoop.mapred.Task

committer, conf, DEFAULT_MR_COMBINE_RECORDS_BEFORE_PROGRESS, FILESYSTEM_COUNTER_GROUP, jobCleanup, jobContext, jobRunStateForCleanup, jobSetup, jvmContext, lDirAlloc, mapOutputFile, MR_COMBINE_RECORDS_BEFORE_PROGRESS, outputFormat, PROGRESS_INTERVAL, spilledRecordsCounter, taskCleanup, taskContext, tokenSecret, umbilical

Constructor Summary

Constructors

Constructor and Description
MapTask()
MapTask(String jobFile, TaskAttemptID taskId, int partition, JobSplit.TaskSplitIndex splitIndex, int numSlotsRequired)

Method Summary

Methods

Modifier and Type	Method and Description
org.apache.hadoop.mapred.TaskRunner	createRunner(TaskTracker tracker, org.apache.hadoop.mapred.TaskTracker.TaskInProgress tip, org.apache.hadoop.mapred.TaskTracker.RunningJob rjob) Return an approprate thread runner for this task.
boolean	isMapTask()
void	readFields(DataInput in)
void	run(JobConf job, TaskUmbilicalProtocol umbilical) Run this task as a part of the named job.
void	write(DataOutput out)
void	writeFilesRequiredForRerun(JobConf conf) Write files that the IsolationRunner will need to rerun the task.

Methods inherited from class org.apache.hadoop.mapred.Task

createReduceContext, done, getConf, getFileSystemCounterNames, getJobFile, getJobID, getJobTokenSecret, getJvmContext, getMapOutputFile, getNumSlotsRequired, getPartition, getPhase, getProgress, getSkipRanges, getTaskID, getUser, initialize, isSkipping, localizeConfiguration, reportFatalError, reportNextRecordRange, runJobCleanupTask, runJobSetupTask, runTaskCleanupTask, setConf, setJobFile, setJobTokenSecret, setJvmContext, setPhase, setSkipping, setSkipRanges, setWriteSkipRecs, statusUpdate, supportIsolationRunner, toString, toWriteSkipRecs

Methods inherited from class java.lang.Object

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

Field Detail

MAP_OUTPUT_INDEX_RECORD_LENGTH

public static final int MAP_OUTPUT_INDEX_RECORD_LENGTH

The size of each record in the index file for the map-outputs.

See Also:

Constant Field Values

Constructor Detail

MapTask

public MapTask()

MapTask

public MapTask(String jobFile,
       TaskAttemptID taskId,
       int partition,
       JobSplit.TaskSplitIndex splitIndex,
       int numSlotsRequired)

Method Detail

isMapTask

public boolean isMapTask()

Specified by:

isMapTask in class Task

writeFilesRequiredForRerun

public void writeFilesRequiredForRerun(JobConf conf)
                                throws IOException

Description copied from class: Task

Write files that the IsolationRunner will need to rerun the task.

Overrides:

writeFilesRequiredForRerun in class Task

Throws:

IOException

createRunner

public org.apache.hadoop.mapred.TaskRunner createRunner(TaskTracker tracker,
                                               org.apache.hadoop.mapred.TaskTracker.TaskInProgress tip,
                                               org.apache.hadoop.mapred.TaskTracker.RunningJob rjob)
                                                 throws IOException

Description copied from class: Task

Return an approprate thread runner for this task.

Specified by:

createRunner in class Task

tip - TODO

Throws:

IOException

write

public void write(DataOutput out)
           throws IOException

Specified by:

write in interface org.apache.hadoop.io.Writable

Overrides:

write in class Task

Throws:

IOException

readFields

public void readFields(DataInput in)
                throws IOException

Specified by:

readFields in interface org.apache.hadoop.io.Writable

Overrides:

readFields in class Task

Throws:

IOException

run

public void run(JobConf job,
       TaskUmbilicalProtocol umbilical)
         throws IOException,
                ClassNotFoundException,
                InterruptedException

Description copied from class: Task

Run this task as a part of the named job. This method is executed in the child process and is what invokes user-supplied map, reduce, etc. methods.

Specified by:

run in class Task

umbilical - for progress reports

Throws:

IOException

ClassNotFoundException

InterruptedException