Package 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:
Comparable<ID>, Writable, WritableComparable<ID>
@Public @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:

  • Constructor Details

    • 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 Details

    • 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
      Returns:
      the JobID object

    • 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