## Package org.apache.hadoop.mapreduce

Class Summary
ClusterMetrics: Status information on the current state of the Map-Reduce cluster.
Counter: A named counter that tracks the progress of a map/reduce job.
CounterGroup: A group of `Counter`s that logically belong together.
Counters
ID: A general identifier, which internally stores the id as an integer.
InputFormat<K,V>: `InputFormat` describes the input-specification for a Map-Reduce job.
InputSplit: `InputSplit` represents the data to be processed by an individual `Mapper`.
Job: The job submitter's view of the Job.
JobContext: A read-only view of the job that is provided to the tasks while they are running.
JobID: JobID represents the immutable and unique identifier for the job.
JobStatus: Describes the current status of a job.
JobSubmissionFiles: A utility to manage job submission files. Note that this class is for framework internal usage only and is not to be used by users directly.
MapContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT>: The context that is given to the `Mapper`.
Mapper<KEYIN,VALUEIN,KEYOUT,VALUEOUT>: Maps input key/value pairs to a set of intermediate key/value pairs.
OutputCommitter: `OutputCommitter` describes the commit of task output for a Map-Reduce job.
OutputFormat<K,V>: `OutputFormat` describes the output-specification for a Map-Reduce job.
Partitioner<KEY,VALUE>: Partitions the key space.
RecordReader<KEYIN,VALUEIN>: The record reader breaks the data into key/value pairs for input to the `Mapper`.
RecordWriter<K,V>: `RecordWriter` writes the output <key, value> pairs to an output file.
ReduceContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT>: The context passed to the `Reducer`.
Reducer<KEYIN,VALUEIN,KEYOUT,VALUEOUT>: Reduces a set of intermediate values which share a key to a smaller set of values.
StatusReporter
TaskAttemptContext: The context for task attempts.
TaskAttemptID: TaskAttemptID represents the immutable and unique identifier for a task attempt.
TaskID: TaskID represents the immutable and unique identifier for a Map or Reduce Task.
TaskInputOutputContext<KEYIN,VALUEIN,KEYOUT,VALUEOUT>: A context object that allows input and output from the task.

Enum Summary
Job.JobState
JobACL: Job related ACLs
JobStatus.State: Current state of the job
TaskType: Enum for map, reduce, job-setup, job-cleanup, task-cleanup task types.

Copyright © 2009 The Apache Software Foundation