org.apache.hadoop.mapred
Class Task

java.lang.Object
  org.apache.hadoop.mapred.Task

All Implemented Interfaces:

org.apache.hadoop.conf.Configurable, org.apache.hadoop.io.Writable

Direct Known Subclasses:

ReduceTask

@InterfaceAudience.LimitedPrivate(value="MapReduce")
@InterfaceStability.Unstable
public abstract class Task
extends Object
implements org.apache.hadoop.io.Writable, org.apache.hadoop.conf.Configurable

Base class for tasks.

Nested Class Summary

static class	Task.CombineOutputCollector<K,V> OutputCollector for the combiner.
protected static class	Task.CombinerRunner<K,V>
static class	Task.CombineValuesIterator<KEY,VALUE> Iterator to return Combined values
static class	Task.Counter Deprecated. Provided for compatibility. Use TaskCounter instead.
protected static class	Task.NewCombinerRunner<K,V>
protected static class	Task.OldCombinerRunner<K,V>
protected class	Task.TaskReporter

Field Summary

protected OutputCommitter	committer
protected JobConf	conf
static long	DEFAULT_COMBINE_RECORDS_BEFORE_PROGRESS
protected org.apache.hadoop.io.BytesWritable	extraData
protected Counters.Counter	failedShuffleCounter
protected static String	FILESYSTEM_COUNTER_GROUP Name of the FileSystem counters' group
protected org.apache.hadoop.mapred.Task.GcTimeUpdater	gcUpdater
protected boolean	jobCleanup
protected JobContext	jobContext
protected JobStatus.State	jobRunStateForCleanup
protected boolean	jobSetup
protected org.apache.hadoop.fs.LocalDirAllocator	lDirAlloc
protected MapOutputFile	mapOutputFile
static String	MERGED_OUTPUT_PREFIX
protected Counters.Counter	mergedMapOutputsCounter
protected OutputFormat<?,?>	outputFormat
static int	PROGRESS_INTERVAL The number of milliseconds between progress reports.
protected Counters.Counter	spilledRecordsCounter
protected boolean	taskCleanup
protected TaskAttemptContext	taskContext
protected SecretKey	tokenSecret
protected TaskUmbilicalProtocol	umbilical

Constructor Summary

Task()

Task(String jobFile, TaskAttemptID taskId, int partition, int numSlotsRequired)

Method Summary

protected static <INKEY,INVALUE,OUTKEY,OUTVALUE> Reducer.Context	createReduceContext(Reducer<INKEY,INVALUE,OUTKEY,OUTVALUE> reducer, org.apache.hadoop.conf.Configuration job, TaskAttemptID taskId, RawKeyValueIterator rIter, Counter inputKeyCounter, Counter inputValueCounter, RecordWriter<OUTKEY,OUTVALUE> output, OutputCommitter committer, StatusReporter reporter, org.apache.hadoop.io.RawComparator<INKEY> comparator, Class<INKEY> keyClass, Class<INVALUE> valueClass)
void	done(TaskUmbilicalProtocol umbilical, Task.TaskReporter reporter)
org.apache.hadoop.conf.Configuration	getConf()
protected static String[]	getFileSystemCounterNames(String uriScheme) Counters to measure the usage of the different file systems.
protected static List<org.apache.hadoop.fs.FileSystem.Statistics>	getFsStatistics(org.apache.hadoop.fs.Path path, org.apache.hadoop.conf.Configuration conf) Gets a handle to the Statistics instance based on the scheme associated with path.
String	getJobFile()
JobID	getJobID() Get the job name for this task.
SecretKey	getJobTokenSecret() Get the job token secret
MapOutputFile	getMapOutputFile()
int	getNumSlotsRequired()
int	getPartition() Get the index of this task within the job.
TaskStatus.Phase	getPhase() Return current phase of the task.
org.apache.hadoop.util.Progress	getProgress()
org.apache.hadoop.mapred.SortedRanges	getSkipRanges() Get skipRanges.
TaskAttemptID	getTaskID()
void	initialize(JobConf job, JobID id, Reporter reporter, boolean useNewApi)
abstract boolean	isMapTask()
boolean	isSkipping() Is Task in skipping mode.
protected boolean	keepTaskFiles(JobConf conf)
void	localizeConfiguration(JobConf conf) Localize the given JobConf to be specific for this task.
void	readFields(DataInput in)
protected void	reportFatalError(TaskAttemptID id, Throwable throwable, String logMsg) Report a fatal error to the parent (task) tracker.
protected void	reportNextRecordRange(TaskUmbilicalProtocol umbilical, long nextRecIndex) Reports the next executing record range to TaskTracker.
abstract void	run(JobConf job, TaskUmbilicalProtocol umbilical) Run this task as a part of the named job.
protected void	runJobCleanupTask(TaskUmbilicalProtocol umbilical, Task.TaskReporter reporter)
protected void	runJobSetupTask(TaskUmbilicalProtocol umbilical, Task.TaskReporter reporter)
protected void	runTaskCleanupTask(TaskUmbilicalProtocol umbilical, Task.TaskReporter reporter)
void	setConf(org.apache.hadoop.conf.Configuration conf)
void	setJobFile(String jobFile)
void	setJobTokenSecret(SecretKey tokenSecret) Set the job token secret
protected void	setPhase(TaskStatus.Phase phase) Set current phase of the task.
void	setSkipping(boolean skipping) Sets whether to run Task in skipping mode.
void	setSkipRanges(org.apache.hadoop.mapred.SortedRanges skipRanges) Set skipRanges.
protected void	setWriteSkipRecs(boolean writeSkipRecs) Set whether to write skip records.
void	statusUpdate(TaskUmbilicalProtocol umbilical) Send a status update to the task tracker
String	toString()
protected boolean	toWriteSkipRecs() Get whether to write skip records.
void	write(DataOutput out)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

MERGED_OUTPUT_PREFIX

public static String MERGED_OUTPUT_PREFIX

DEFAULT_COMBINE_RECORDS_BEFORE_PROGRESS

public static final long DEFAULT_COMBINE_RECORDS_BEFORE_PROGRESS

See Also:

Constant Field Values

FILESYSTEM_COUNTER_GROUP

protected static final String FILESYSTEM_COUNTER_GROUP

Name of the FileSystem counters' group

See Also:

Constant Field Values

jobRunStateForCleanup

protected JobStatus.State jobRunStateForCleanup

jobCleanup

protected boolean jobCleanup

jobSetup

protected boolean jobSetup

taskCleanup

protected boolean taskCleanup

extraData

protected org.apache.hadoop.io.BytesWritable extraData

conf

protected JobConf conf

mapOutputFile

protected MapOutputFile mapOutputFile

lDirAlloc

protected org.apache.hadoop.fs.LocalDirAllocator lDirAlloc

jobContext

protected JobContext jobContext

taskContext

protected TaskAttemptContext taskContext

outputFormat

protected OutputFormat<?,?> outputFormat

committer

protected OutputCommitter committer

spilledRecordsCounter

protected final Counters.Counter spilledRecordsCounter

failedShuffleCounter

protected final Counters.Counter failedShuffleCounter

mergedMapOutputsCounter

protected final Counters.Counter mergedMapOutputsCounter

umbilical

protected TaskUmbilicalProtocol umbilical

tokenSecret

protected SecretKey tokenSecret

gcUpdater

protected org.apache.hadoop.mapred.Task.GcTimeUpdater gcUpdater

PROGRESS_INTERVAL

public static final int PROGRESS_INTERVAL

The number of milliseconds between progress reports.

See Also:

Constant Field Values

Constructor Detail

Task

public Task()

Task

public Task(String jobFile,
            TaskAttemptID taskId,
            int partition,
            int numSlotsRequired)

Method Detail

getFileSystemCounterNames

protected static String[] getFileSystemCounterNames(String uriScheme)

Counters to measure the usage of the different file systems. Always return the String array with two elements. First one is the name of BYTES_READ counter and second one is of the BYTES_WRITTEN counter.

setJobFile

public void setJobFile(String jobFile)

getJobFile

public String getJobFile()

getTaskID

public TaskAttemptID getTaskID()

getNumSlotsRequired

public int getNumSlotsRequired()

getJobID

public JobID getJobID()

Get the job name for this task.

Returns:

the job name

setJobTokenSecret

public void setJobTokenSecret(SecretKey tokenSecret)

Set the job token secret

Parameters:

tokenSecret - the secret

getJobTokenSecret

public SecretKey getJobTokenSecret()

Get the job token secret

Returns:

the token secret

getPartition

public int getPartition()

Get the index of this task within the job.

Returns:

the integer part of the task id

getPhase

public TaskStatus.Phase getPhase()

Return current phase of the task. needs to be synchronized as communication thread sends the phase every second

Returns:

the curent phase of the task

setPhase

protected void setPhase(TaskStatus.Phase phase)

Set current phase of the task.

Parameters:

phase - task phase

toWriteSkipRecs

protected boolean toWriteSkipRecs()

Get whether to write skip records.

setWriteSkipRecs

protected void setWriteSkipRecs(boolean writeSkipRecs)

Set whether to write skip records.

reportFatalError

protected void reportFatalError(TaskAttemptID id,
                                Throwable throwable,
                                String logMsg)

Report a fatal error to the parent (task) tracker.

getFsStatistics

protected static List<org.apache.hadoop.fs.FileSystem.Statistics> getFsStatistics(org.apache.hadoop.fs.Path path,
                                                                                  org.apache.hadoop.conf.Configuration conf)
                                                                           throws IOException

Gets a handle to the Statistics instance based on the scheme associated with path.

Parameters:

path - the path.

conf - the configuration to extract the scheme from if not part of the path.

Returns:

a Statistics instance, or null if none is found for the scheme.

Throws:

IOException

getSkipRanges

public org.apache.hadoop.mapred.SortedRanges getSkipRanges()

Get skipRanges.

setSkipRanges

public void setSkipRanges(org.apache.hadoop.mapred.SortedRanges skipRanges)

Set skipRanges.

isSkipping

public boolean isSkipping()

Is Task in skipping mode.

setSkipping

public void setSkipping(boolean skipping)

Sets whether to run Task in skipping mode.

Parameters:

skipping -

write

public void write(DataOutput out)
           throws IOException

Specified by:

write in interface org.apache.hadoop.io.Writable

Throws:

IOException

readFields

public void readFields(DataInput in)
                throws IOException

Specified by:

readFields in interface org.apache.hadoop.io.Writable

Throws:

IOException

toString

public String toString()

Overrides:

toString in class Object

localizeConfiguration

public void localizeConfiguration(JobConf conf)
                           throws IOException

Localize the given JobConf to be specific for this task.

Throws:

IOException

run

public abstract void run(JobConf job,
                         TaskUmbilicalProtocol umbilical)
                  throws IOException,
                         ClassNotFoundException,
                         InterruptedException

Run this task as a part of the named job. This method is executed in the child process and is what invokes user-supplied map, reduce, etc. methods.

Parameters:

umbilical - for progress reports

Throws:

IOException

ClassNotFoundException

InterruptedException

isMapTask

public abstract boolean isMapTask()

getProgress

public org.apache.hadoop.util.Progress getProgress()

initialize

public void initialize(JobConf job,
                       JobID id,
                       Reporter reporter,
                       boolean useNewApi)
                throws IOException,
                       ClassNotFoundException,
                       InterruptedException

Throws:

IOException

ClassNotFoundException

InterruptedException

reportNextRecordRange

protected void reportNextRecordRange(TaskUmbilicalProtocol umbilical,
                                     long nextRecIndex)
                              throws IOException

Reports the next executing record range to TaskTracker.

Parameters:

umbilical -

nextRecIndex - the record index which would be fed next.

Throws:

IOException

done

public void done(TaskUmbilicalProtocol umbilical,
                 Task.TaskReporter reporter)
          throws IOException,
                 InterruptedException

Throws:

IOException

InterruptedException

statusUpdate

public void statusUpdate(TaskUmbilicalProtocol umbilical)
                  throws IOException

Send a status update to the task tracker

Parameters:

umbilical -

Throws:

IOException

runTaskCleanupTask

protected void runTaskCleanupTask(TaskUmbilicalProtocol umbilical,
                                  Task.TaskReporter reporter)
                           throws IOException,
                                  InterruptedException

Throws:

IOException

InterruptedException

runJobCleanupTask

protected void runJobCleanupTask(TaskUmbilicalProtocol umbilical,
                                 Task.TaskReporter reporter)
                          throws IOException,
                                 InterruptedException

Throws:

IOException

InterruptedException

keepTaskFiles

protected boolean keepTaskFiles(JobConf conf)

runJobSetupTask

protected void runJobSetupTask(TaskUmbilicalProtocol umbilical,
                               Task.TaskReporter reporter)
                        throws IOException,
                               InterruptedException

Throws:

IOException

InterruptedException

setConf

public void setConf(org.apache.hadoop.conf.Configuration conf)

Specified by:

setConf in interface org.apache.hadoop.conf.Configurable

getConf

public org.apache.hadoop.conf.Configuration getConf()

Specified by:

getConf in interface org.apache.hadoop.conf.Configurable

getMapOutputFile

public MapOutputFile getMapOutputFile()

createReduceContext

protected static <INKEY,INVALUE,OUTKEY,OUTVALUE> Reducer.Context createReduceContext(Reducer<INKEY,INVALUE,OUTKEY,OUTVALUE> reducer,
                                                                                     org.apache.hadoop.conf.Configuration job,
                                                                                     TaskAttemptID taskId,
                                                                                     RawKeyValueIterator rIter,
                                                                                     Counter inputKeyCounter,
                                                                                     Counter inputValueCounter,
                                                                                     RecordWriter<OUTKEY,OUTVALUE> output,
                                                                                     OutputCommitter committer,
                                                                                     StatusReporter reporter,
                                                                                     org.apache.hadoop.io.RawComparator<INKEY> comparator,
                                                                                     Class<INKEY> keyClass,
                                                                                     Class<INVALUE> valueClass)
                                              throws IOException,
                                                     InterruptedException

Throws:

IOException

InterruptedException