org.apache.hadoop.mapred
Class MapTask

java.lang.Object
  extended by org.apache.hadoop.mapred.Task
      extended by 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
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
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
MapTask()
           
MapTask(java.lang.String jobFile, TaskAttemptID taskId, int partition, JobSplit.TaskSplitIndex splitIndex, int numSlotsRequired)
           
 
Method Summary
 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(java.io.DataInput in)
           
 void run(JobConf job, TaskUmbilicalProtocol umbilical)
          Run this task as a part of the named job.
 void write(java.io.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(java.lang.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 java.io.IOException
Description copied from class: Task
Write files that the IsolationRunner will need to rerun the task.

Overrides:
writeFilesRequiredForRerun in class Task
Throws:
java.io.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 java.io.IOException
Description copied from class: Task
Return an approprate thread runner for this task.

Specified by:
createRunner in class Task
tip - TODO
Throws:
java.io.IOException

write

public void write(java.io.DataOutput out)
           throws java.io.IOException
Specified by:
write in interface org.apache.hadoop.io.Writable
Overrides:
write in class Task
Throws:
java.io.IOException

readFields

public void readFields(java.io.DataInput in)
                throws java.io.IOException
Specified by:
readFields in interface org.apache.hadoop.io.Writable
Overrides:
readFields in class Task
Throws:
java.io.IOException

run

public void run(JobConf job,
                TaskUmbilicalProtocol umbilical)
         throws java.io.IOException,
                java.lang.ClassNotFoundException,
                java.lang.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:
java.io.IOException
java.lang.ClassNotFoundException
java.lang.InterruptedException


Copyright © 2009 The Apache Software Foundation