Class JobSplit

  extended by org.apache.hadoop.mapreduce.split.JobSplit

public class JobSplit
extends Object

This class groups the fundamental classes associated with reading/writing splits. The split information is divided into two parts based on the consumer of the information. The two parts are the split meta information, and the raw split information. The first part is consumed by the JobTracker to create the tasks' locality data structures. The second part is used by the maps at runtime to know what to do! These pieces of information are written to two separate files. The metainformation file is slurped by the JobTracker during job initialization. A map task gets the meta information during the launch and it reads the raw split bytes directly from the file.

Nested Class Summary
static class JobSplit.SplitMetaInfo
          This represents the meta information about the task split.
static class JobSplit.TaskSplitIndex
          This represents the meta information about the task split that the task gets
static class JobSplit.TaskSplitMetaInfo
          This represents the meta information about the task split that the JobTracker creates
Field Summary
static JobSplit.TaskSplitMetaInfo EMPTY_TASK_SPLIT
Constructor Summary
Method Summary
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail


public static final JobSplit.TaskSplitMetaInfo EMPTY_TASK_SPLIT
Constructor Detail


public JobSplit()

Copyright © 2009 The Apache Software Foundation