| Class and Description | 
|---|
| AMFeedback This class is a simple struct to include both the taskFound information and
 a possible preemption request coming from the AM. | 
| ClusterStatus Status information on the current state of the Map-Reduce cluster. | 
| ClusterStatus.BlackListInfo Class which encapsulates information about a blacklisted tasktracker. | 
| Counters A set of named counters. | 
| Counters.Counter A counter record, comprising its name and value. | 
| Counters.CountersExceededException Counter exception thrown when the number of counters exceed the limit | 
| Counters.Group Groupof counters, comprising of counters from a particular
  counterEnumclass. | 
| FileInputFormat A base class for file-based  InputFormat. | 
| FileInputFormat.Counter Deprecated.  | 
| FileOutputFormat A base class for  OutputFormat. | 
| FileOutputFormat.Counter Deprecated.  | 
| FileSplit A section of an input file. | 
| IFile.Reader IFile.Readerto read intermediate map-outputs. | 
| IFile.Writer IFile.Writerto write out intermediate map-outputs. | 
| IndexRecord | 
| InputFormat InputFormatdescribes the input-specification for a 
 Map-Reduce job. | 
| InputSplit InputSplitrepresents the data to be processed by an 
 individualMapper. | 
| InputSplitWithLocationInfo | 
| InvalidJobConfException This exception is thrown when jobconf misses some mendatory attributes
 or value of some attributes is invalid. | 
| JobClient.TaskStatusFilter | 
| JobConf A map/reduce job configuration. | 
| JobConfigurable That what may be configured. | 
| JobContext | 
| JobID JobID represents the immutable and unique identifier for 
 the job. | 
| JobInProgress.Counter Deprecated. 
 Provided for compatibility. Use  JobCounterinstead. | 
| JobPriority Used to describe the priority of the running job. | 
| JobQueueInfo Class that contains the information regarding the Job Queues which are 
 maintained by the Hadoop Map/Reduce framework. | 
| JobStatus Describes the current status of a job. | 
| JobTracker.State Stateis no longer used since M/R 2.x. | 
| JvmTask Task abstraction that can be serialized, implements the writable interface. | 
| MapOutputCollector | 
| MapOutputCollector.Context | 
| MapOutputFile Manipulate the working area for the transient store for maps and reduces. | 
| Mapper Maps input key/value pairs to a set of intermediate key/value pairs. | 
| MapRunnable Expert: Generic interface for  Mappers. | 
| MapTask A Map task. | 
| MapTaskCompletionEventsUpdate A class that represents the communication between the tasktracker and child
 tasks w.r.t the map task completion events. | 
| Master.State | 
| Merger.Segment | 
| Operation Generic operation that maps to the dependent set of ACLs that drive the
 authorization of the operation. | 
| OutputCollector | 
| OutputCommitter OutputCommitterdescribes the commit of task output for a 
 Map-Reduce job. | 
| OutputFormat OutputFormatdescribes the output-specification for a 
 Map-Reduce job. | 
| Partitioner Partitions the key space. | 
| QueueACL Enum representing an AccessControlList that drives set of operations that
 can be performed on a queue. | 
| RawKeyValueIterator RawKeyValueIteratoris an iterator used to iterate over
 the raw keys and values during sort/merge of intermediate data. | 
| RecordReader RecordReaderreads <key, value> pairs from anInputSplit. | 
| RecordWriter RecordWriterwrites the output <key, value> pairs 
 to an output file. | 
| Reducer Reduces a set of intermediate values which share a key to a smaller set of
 values. | 
| Reporter A facility for Map-Reduce applications to report progress and update 
 counters, status information etc. | 
| RunningJob RunningJobis the user-interface to query for details on a 
 running Map-Reduce job. | 
| SequenceFileInputFilter.FilterBase base class for Filters | 
| SequenceFileInputFormat An  InputFormatforSequenceFiles. | 
| SequenceFileOutputFormat An  OutputFormatthat writesSequenceFiles. | 
| ShuffleConsumerPlugin.Context | 
| SplitLocationInfo | 
| Task Base class for tasks. | 
| Task.CombineOutputCollector OutputCollector for the combiner. | 
| Task.CombinerRunner | 
| Task.Counter Deprecated. 
 Provided for compatibility. Use  TaskCounterinstead. | 
| Task.TaskReporter | 
| Task.TaskReporter.TaskLimitException exception thrown when the task exceeds some configured limits. | 
| TaskAttemptContext | 
| TaskAttemptID TaskAttemptID represents the immutable and unique identifier for 
 a task attempt. | 
| TaskCompletionEvent This is used to track task completion events on 
 job tracker. | 
| TaskCompletionEvent.Status | 
| TaskID TaskID represents the immutable and unique identifier for 
 a Map or Reduce Task. | 
| TaskLog.LogName The filter for userlogs. | 
| TaskReport A report on the state of a task. | 
| TaskStatus Describes the current status of a task. | 
| TaskStatus.Phase | 
| TaskStatus.State | 
| TaskUmbilicalProtocol Protocol that task child process uses to contact its parent process. | 
| TIPStatus The states of a Tasks. | 
| Utils.OutputFileUtils.OutputLogFilter This class filters log files from directory given
 It doesnt accept paths having _logs. | 
| Class and Description | 
|---|
| JobClient JobClientis the primary interface for the user-job to interact
 with the cluster. | 
| JobConf A map/reduce job configuration. | 
| JobID JobID represents the immutable and unique identifier for 
 the job. | 
| Class and Description | 
|---|
| InputFormat InputFormatdescribes the input-specification for a 
 Map-Reduce job. | 
| InputSplit InputSplitrepresents the data to be processed by an 
 individualMapper. | 
| JobConf A map/reduce job configuration. | 
| RecordReader RecordReaderreads <key, value> pairs from anInputSplit. | 
| Reporter A facility for Map-Reduce applications to report progress and update 
 counters, status information etc. | 
| Class and Description | 
|---|
| FileInputFormat A base class for file-based  InputFormat. | 
| FileOutputFormat A base class for  OutputFormat. | 
| FileSplit A section of an input file. | 
| InputFormat InputFormatdescribes the input-specification for a 
 Map-Reduce job. | 
| InputSplit InputSplitrepresents the data to be processed by an 
 individualMapper. | 
| JobConf A map/reduce job configuration. | 
| JobConfigurable That what may be configured. | 
| Mapper Maps input key/value pairs to a set of intermediate key/value pairs. | 
| MapReduceBase | 
| MapRunnable Expert: Generic interface for  Mappers. | 
| OutputCollector | 
| OutputFormat OutputFormatdescribes the output-specification for a 
 Map-Reduce job. | 
| Partitioner Partitions the key space. | 
| RecordReader RecordReaderreads <key, value> pairs from anInputSplit. | 
| RecordWriter RecordWriterwrites the output <key, value> pairs 
 to an output file. | 
| Reducer Reduces a set of intermediate values which share a key to a smaller set of
 values. | 
| Reporter A facility for Map-Reduce applications to report progress and update 
 counters, status information etc. | 
| Class and Description | 
|---|
| JobConf A map/reduce job configuration. | 
| JobConfigurable That what may be configured. | 
| Mapper Maps input key/value pairs to a set of intermediate key/value pairs. | 
| OutputCollector | 
| Reducer Reduces a set of intermediate values which share a key to a smaller set of
 values. | 
| Reporter A facility for Map-Reduce applications to report progress and update 
 counters, status information etc. | 
| Class and Description | 
|---|
| InputFormat InputFormatdescribes the input-specification for a 
 Map-Reduce job. | 
| InputSplit InputSplitrepresents the data to be processed by an 
 individualMapper. | 
| JobConf A map/reduce job configuration. | 
| JobConfigurable That what may be configured. | 
| OutputFormat OutputFormatdescribes the output-specification for a 
 Map-Reduce job. | 
| RecordReader RecordReaderreads <key, value> pairs from anInputSplit. | 
| RecordWriter RecordWriterwrites the output <key, value> pairs 
 to an output file. | 
| Reporter A facility for Map-Reduce applications to report progress and update 
 counters, status information etc. | 
| Class and Description | 
|---|
| JobConf A map/reduce job configuration. | 
| RunningJob RunningJobis the user-interface to query for details on a 
 running Map-Reduce job. | 
| Class and Description | 
|---|
| ID A general identifier, which internally stores the id
 as an integer. | 
| SplitLocationInfo | 
| TaskCompletionEvent This is used to track task completion events on 
 job tracker. | 
| TaskID TaskID represents the immutable and unique identifier for 
 a Map or Reduce Task. | 
| TIPStatus The states of a Tasks. | 
| Class and Description | 
|---|
| Counters A set of named counters. | 
| Class and Description | 
|---|
| Counters.CountersExceededException Counter exception thrown when the number of counters exceed the limit | 
| Class and Description | 
|---|
| JobConf A map/reduce job configuration. | 
| JobPriority Used to describe the priority of the running job. | 
| Class and Description | 
|---|
| SplitLocationInfo | 
| Class and Description | 
|---|
| FileAlreadyExistsException Used when target file already exists for any operation and 
 is not configured to be overwritten. | 
| Class and Description | 
|---|
| JobConf A map/reduce job configuration. | 
| Class and Description | 
|---|
| InputSplit InputSplitrepresents the data to be processed by an 
 individualMapper. | 
| Class and Description | 
|---|
| JobConf A map/reduce job configuration. | 
| RawKeyValueIterator RawKeyValueIteratoris an iterator used to iterate over
 the raw keys and values during sort/merge of intermediate data. | 
| Class and Description | 
|---|
| Counters.Counter A counter record, comprising its name and value. | 
| IFile.Reader IFile.Readerto read intermediate map-outputs. | 
| IFile.Writer IFile.Writerto write out intermediate map-outputs. | 
| IFileInputStream A checksum input stream, used for IFiles. | 
| JobConf A map/reduce job configuration. | 
| MapOutputFile Manipulate the working area for the transient store for maps and reduces. | 
| RawKeyValueIterator RawKeyValueIteratoris an iterator used to iterate over
 the raw keys and values during sort/merge of intermediate data. | 
| Reducer Reduces a set of intermediate values which share a key to a smaller set of
 values. | 
| Reporter A facility for Map-Reduce applications to report progress and update 
 counters, status information etc. | 
| ShuffleConsumerPlugin ShuffleConsumerPlugin for serving Reducers. | 
| ShuffleConsumerPlugin.Context | 
| Task.CombineOutputCollector OutputCollector for the combiner. | 
| TaskCompletionEvent This is used to track task completion events on 
 job tracker. | 
| TaskStatus Describes the current status of a task. | 
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