org.apache.hadoop.mapred
Class TaskID

java.lang.Object
  extended by org.apache.hadoop.mapreduce.ID
      extended by org.apache.hadoop.mapred.ID
          extended by org.apache.hadoop.mapreduce.TaskID
              extended by org.apache.hadoop.mapred.TaskID
All Implemented Interfaces:
Comparable<ID>, Writable, WritableComparable<ID>

@InterfaceAudience.Public
@InterfaceStability.Stable
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
TaskID()
           
TaskID(JobID jobId, boolean isMap, int id)
          Deprecated. Use TaskID(String, int, TaskType, int)
TaskID(JobID jobId, TaskType type, int id)
          Constructs a TaskID object from given JobID.
TaskID(String jtIdentifier, int jobId, boolean isMap, int id)
          Deprecated. Use TaskID(org.apache.hadoop.mapreduce.JobID, TaskType, int)
TaskID(String jtIdentifier, int jobId, TaskType type, int id)
          Constructs a TaskInProgressId object from given parts.
 
Method Summary
static TaskID downgrade(TaskID old)
          Downgrade a new TaskID to an old one
static TaskID forName(String str)
           
 JobID getJobID()
          Returns the JobID object that this tip belongs to
static String getTaskIDsPattern(String jtIdentifier, Integer jobId, Boolean isMap, Integer taskId)
          Deprecated. Use getTaskIDsPattern(String, Integer, TaskType, Integer)
static String getTaskIDsPattern(String jtIdentifier, Integer jobId, TaskType type, Integer taskId)
          Deprecated. 
static TaskID read(DataInput in)
          Deprecated. 
 
Methods inherited from class org.apache.hadoop.mapreduce.TaskID
appendTo, compareTo, equals, getAllTaskTypes, getRepresentingCharacter, getTaskType, 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

@Deprecated
public TaskID(JobID jobId,
                         boolean isMap,
                         int id)
Deprecated. Use TaskID(String, int, TaskType, int)

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

@Deprecated
public TaskID(String jtIdentifier,
                         int jobId,
                         boolean isMap,
                         int id)
Deprecated. Use TaskID(org.apache.hadoop.mapreduce.JobID, TaskType, int)

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(JobID jobId,
              TaskType type,
              int id)
Constructs a TaskID object from given JobID.

Parameters:
jobId - JobID that this tip belongs to
type - the TaskType
id - the tip number

TaskID

public TaskID(String jtIdentifier,
              int jobId,
              TaskType type,
              int id)
Constructs a TaskInProgressId object from given parts.

Parameters:
jtIdentifier - jobTracker identifier
jobId - job number
type - the TaskType
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(DataInput in)
                   throws IOException
Deprecated. 

Throws:
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 String getTaskIDsPattern(String jtIdentifier,
                                                  Integer jobId,
                                                  Boolean isMap,
                                                  Integer taskId)
Deprecated. Use getTaskIDsPattern(String, Integer, TaskType, Integer)

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

getTaskIDsPattern

@Deprecated
public static String getTaskIDsPattern(String jtIdentifier,
                                                  Integer jobId,
                                                  TaskType type,
                                                  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
type - the TaskType, or null
taskId - taskId number, or null
Returns:
a regex pattern matching TaskIDs

forName

public static TaskID forName(String str)
                      throws IllegalArgumentException
Throws:
IllegalArgumentException


Copyright © 2012 Apache Software Foundation. All Rights Reserved.