org.apache.hadoop.mapred
Class TaskAttemptID

java.lang.Object
  org.apache.hadoop.mapred.ID
      org.apache.hadoop.mapred.TaskAttemptID

All Implemented Interfaces:

Comparable<ID>, Writable, WritableComparable<ID>

public class TaskAttemptID
extends ID

TaskAttemptID represents the immutable and unique identifier for a task attempt. Each task attempt is one particular instance of a Map or Reduce Task identified by its TaskID. TaskAttemptID consists of 2 parts. First part is the TaskID, that this TaskAttemptID belongs to. Second part is the task attempt number.
An example TaskAttemptID is : attempt_200707121733_0003_m_000005_0 , which represents the zeroth task attempt for the fifth map task in the third job running at the jobtracker started at 200707121733.

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

See Also:

JobID, TaskID

Field Summary

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

id

Constructor Summary

TaskAttemptID(String jtIdentifier, int jobId, boolean isMap, int taskId, int id)
Constructs a TaskId object from given parts.

TaskAttemptID(TaskID taskId, int id)
Constructs a TaskAttemptID object from given TaskID.

Method Summary

int	compareTo(ID o) Compare TaskIds by first tipIds, then by task numbers.
boolean	equals(Object o)
static TaskAttemptID	forName(String str) Construct a TaskAttemptID object from given string
JobID	getJobID() Returns the JobID object that this task attempt belongs to
static String	getTaskAttemptIDsPattern(String jtIdentifier, Integer jobId, Boolean isMap, Integer taskId, Integer attemptId) Returns a regex pattern which matches task attempt IDs.
TaskID	getTaskID() Returns the TaskID object that this task attempt belongs to
int	hashCode()
boolean	isMap() Returns whether this TaskAttemptID is a map ID
static TaskAttemptID	read(DataInput in)
void	readFields(DataInput in) Deserialize the fields of this object from in.
String	toString()
void	write(DataOutput out) Serialize the fields of this object to out.

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

getId

Methods inherited from class java.lang.Object

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

Constructor Detail

TaskAttemptID

public TaskAttemptID(TaskID taskId,
                     int id)

Constructs a TaskAttemptID object from given TaskID.

Parameters:

taskId - TaskID that this task belongs to

id - the task attempt number

TaskAttemptID

public TaskAttemptID(String jtIdentifier,
                     int jobId,
                     boolean isMap,
                     int taskId,
                     int id)

Constructs a TaskId object from given parts.

Parameters:

jtIdentifier - jobTracker identifier

jobId - job number

isMap - whether the tip is a map

taskId - taskId number

id - the task attempt number

Method Detail

getJobID

public JobID getJobID()

Returns the JobID object that this task attempt belongs to

getTaskID

public TaskID getTaskID()

Returns the TaskID object that this task attempt belongs to

isMap

public boolean isMap()

Returns whether this TaskAttemptID is a map ID

equals

public boolean equals(Object o)

Overrides:

equals in class ID

compareTo

public int compareTo(ID o)

Compare TaskIds by first tipIds, then by task numbers.

Specified by:

compareTo in interface Comparable<ID>

Overrides:

compareTo in class ID

toString

public String toString()

Overrides:

toString in class ID

hashCode

public int hashCode()

Overrides:

hashCode in class ID

readFields

public void readFields(DataInput in)
                throws IOException

Description copied from interface: Writable

Deserialize the fields of this object from in.

For efficiency, implementations should attempt to re-use storage in the existing object where possible.

Specified by:

readFields in interface Writable

Overrides:

readFields in class ID

Parameters:

in - DataInput to deseriablize this object from.

Throws:

IOException

write

public void write(DataOutput out)
           throws IOException

Description copied from interface: Writable

Serialize the fields of this object to out.

Specified by:

write in interface Writable

Overrides:

write in class ID

Parameters:

out - DataOuput to serialize this object into.

Throws:

IOException

read

public static TaskAttemptID read(DataInput in)
                          throws IOException

Throws:

IOException

forName

public static TaskAttemptID forName(String str)
                             throws IllegalArgumentException

Construct a TaskAttemptID object from given string

Returns:

constructed TaskAttemptID object or null if the given String is null

Throws:

IllegalArgumentException - if the given string is malformed

getTaskAttemptIDsPattern

public static String getTaskAttemptIDsPattern(String jtIdentifier,
                                              Integer jobId,
                                              Boolean isMap,
                                              Integer taskId,
                                              Integer attemptId)

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

 
 TaskAttemptID.getTaskAttemptIDsPattern(null, null, true, 1, null);
 

which will return :

 "attempt_[^_]*_[0-9]*_m_000001_[0-9]*" 

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

attemptId - the task attempt number, or null

Returns:

a regex pattern matching TaskAttemptIDs