org.apache.hadoop.mapreduce

类 TaskID

java.lang.Object

org.apache.hadoop.mapreduce.ID

org.apache.hadoop.mapred.ID

org.apache.hadoop.mapreduce.TaskID

所有已实现的接口:

Comparable<ID>, Writable, WritableComparable<ID>

直接已知子类:

TaskID

public class TaskID
extends ID

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.

另请参阅:

JobID, TaskAttemptID

字段概要

字段

限定符和类型	字段和说明
protected static NumberFormat	idFormat
protected static String	TASK

从类继承的字段 org.apache.hadoop.mapreduce.ID

id, SEPARATOR

构造器概要

构造器

构造器和说明
TaskID()
TaskID(JobID jobId, boolean isMap, int id) Constructs a TaskID object from given JobID.
TaskID(String jtIdentifier, int jobId, boolean isMap, int id) Constructs a TaskInProgressId object from given parts.

方法概要

方法

限定符和类型	方法和说明
protected StringBuilder	appendTo(StringBuilder builder) Add the unique string to the given builder.
int	compareTo(ID o) Compare TaskInProgressIds by first jobIds, then by tip numbers.
boolean	equals(Object o)
static TaskID	forName(String str) Construct a TaskID object from given string
JobID	getJobID() Returns the JobID object that this tip belongs to
int	hashCode()
boolean	isMap() Returns whether this TaskID is a map ID
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.

从类继承的方法 org.apache.hadoop.mapreduce.ID

getId

从类继承的方法 java.lang.Object

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

字段详细资料

TASK

protected static final String TASK

另请参阅:

常量字段值

idFormat

protected static final NumberFormat idFormat

构造器详细资料

TaskID

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

Constructs a TaskID object from given JobID.

参数:

jobId - JobID that this tip belongs to

isMap - whether the tip is a map

id - the tip number

TaskID

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

Constructs a TaskInProgressId object from given parts.

参数:

jtIdentifier - jobTracker identifier

jobId - job number

isMap - whether the tip is a map

id - the tip number

TaskID

public TaskID()

方法详细资料

getJobID

public JobID getJobID()

Returns the JobID object that this tip belongs to

isMap

public boolean isMap()

Returns whether this TaskID is a map ID

equals

public boolean equals(Object o)

覆盖:

equals 在类中 ID

compareTo

public int compareTo(ID o)

Compare TaskInProgressIds by first jobIds, then by tip numbers. Reduces are defined as greater then maps.

指定者:

compareTo 在接口中 Comparable<ID>

覆盖:

compareTo 在类中 ID

toString

public String toString()

覆盖:

toString 在类中 ID

appendTo

protected StringBuilder appendTo(StringBuilder builder)

Add the unique string to the given builder.

参数:

builder - the builder to append to

返回:

the builder that was passed in

hashCode

public int hashCode()

覆盖:

hashCode 在类中 ID

readFields

public void readFields(DataInput in)
                throws IOException

从接口复制的说明: Writable

Deserialize the fields of this object from in.

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

指定者:

readFields 在接口中 Writable

覆盖:

readFields 在类中 ID

参数:

in - DataInput to deseriablize this object from.

抛出:

IOException

write

public void write(DataOutput out)
           throws IOException

从接口复制的说明: Writable

Serialize the fields of this object to out.

指定者:

write 在接口中 Writable

覆盖:

write 在类中 ID

参数:

out - DataOuput to serialize this object into.

抛出:

IOException

forName

public static TaskID forName(String str)
                      throws IllegalArgumentException

Construct a TaskID object from given string

返回:

constructed TaskID object or null if the given String is null

抛出:

IllegalArgumentException - if the given string is malformed