org.apache.hadoop.mapred

Class TaskID

java.lang.Object

org.apache.hadoop.mapreduce.ID

org.apache.hadoop.mapred.ID

org.apache.hadoop.mapreduce.TaskID

org.apache.hadoop.mapred.TaskID

All Implemented Interfaces:

java.lang.Comparable<ID>, org.apache.hadoop.io.Writable, org.apache.hadoop.io.WritableComparable<ID>

public class TaskID
extends TaskID

TaskID represents the immutable and unique identifier for a Map or Reduce Task. Each TaskID encompasses multiple attempts made to execute the Map or Reduce Task, each of which are uniquely indentified by their TaskAttemptID. TaskID consists of 3 parts. First part is the JobID, that this TaskInProgress belongs to. Second part of the TaskID is either 'm' or 'r' representing whether the task is a map task or a reduce task. And the third part is the task number.
An example TaskID is : task_200707121733_0003_m_000005 , which represents the fifth map task in the third job running at the jobtracker started at 200707121733.

Applications should never construct or parse TaskID strings , but rather use appropriate constructors or forName(String) method.

See Also:

JobID, TaskAttemptID

Field Summary

Fields inherited from class org.apache.hadoop.mapreduce.TaskID

idFormat, TASK

Fields inherited from class org.apache.hadoop.mapreduce.ID

id, SEPARATOR

Constructor Summary

Constructors

Constructor and Description
TaskID()
TaskID(JobID jobId, boolean isMap, int id) Constructs a TaskID object from given JobID.
TaskID(java.lang.String jtIdentifier, int jobId, boolean isMap, int id) Constructs a TaskInProgressId object from given parts.

Method Summary

Methods

Modifier and Type	Method and Description
static TaskID	downgrade(TaskID old) Downgrade a new TaskID to an old one
static TaskID	forName(java.lang.String str)
JobID	getJobID() Returns the JobID object that this tip belongs to
static java.lang.String	getTaskIDsPattern(java.lang.String jtIdentifier, java.lang.Integer jobId, java.lang.Boolean isMap, java.lang.Integer taskId) Deprecated.
static TaskID	read(java.io.DataInput in) Deprecated.

Methods inherited from class org.apache.hadoop.mapreduce.TaskID

appendTo, compareTo, equals, getTaskType, hashCode, isMap, readFields, toString, write

Methods inherited from class org.apache.hadoop.mapreduce.ID

getId

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

TaskID

public TaskID(JobID jobId,
      boolean isMap,
      int id)

Constructs a TaskID object from given JobID.

Parameters:

jobId - JobID that this tip belongs to

isMap - whether the tip is a map

id - the tip number

TaskID

public TaskID(java.lang.String jtIdentifier,
      int jobId,
      boolean isMap,
      int id)

Constructs a TaskInProgressId object from given parts.

Parameters:

jtIdentifier - jobTracker identifier

jobId - job number

isMap - whether the tip is a map

id - the tip number

TaskID

public TaskID()

Method Detail

downgrade

public static TaskID downgrade(TaskID old)

Downgrade a new TaskID to an old one

Parameters:

old - a new or old TaskID

Returns:

either old or a new TaskID build to match old

read

@Deprecated
public static TaskID read(java.io.DataInput in)
                   throws java.io.IOException

Deprecated.

Throws:

java.io.IOException

getJobID

public JobID getJobID()

Description copied from class: TaskID

Returns the JobID object that this tip belongs to

Overrides:

getJobID in class TaskID

getTaskIDsPattern

@Deprecated
public static java.lang.String getTaskIDsPattern(java.lang.String jtIdentifier,
                                            java.lang.Integer jobId,
                                            java.lang.Boolean isMap,
                                            java.lang.Integer taskId)

Deprecated.

Returns a regex pattern which matches task IDs. Arguments can be given null, in which case that part of the regex will be generic. For example to obtain a regex matching the first map task of any jobtracker, of any job, we would use :

 
 TaskID.getTaskIDsPattern(null, null, true, 1);
 

which will return :

 "task_[^_]*_[0-9]*_m_000001*" 

Parameters:

jtIdentifier - jobTracker identifier, or null

jobId - job number, or null

isMap - whether the tip is a map, or null

taskId - taskId number, or null

Returns:

a regex pattern matching TaskIDs

forName

public static TaskID forName(java.lang.String str)
                      throws java.lang.IllegalArgumentException

Throws:

java.lang.IllegalArgumentException