org.apache.hadoop.mapreduce.lib.output

Class FileOutputCommitter

java.lang.Object

org.apache.hadoop.mapreduce.OutputCommitter

org.apache.hadoop.mapreduce.lib.output.FileOutputCommitter

Direct Known Subclasses:

PartialFileOutputCommitter

@InterfaceAudience.Public
@InterfaceStability.Stable
public class FileOutputCommitter
extends OutputCommitter

An OutputCommitter that commits files specified in job output directory i.e. ${mapreduce.output.fileoutputformat.outputdir}.

Field Summary

Fields

Modifier and Type	Field and Description
static String	FILEOUTPUTCOMMITTER_ALGORITHM_VERSION
static int	FILEOUTPUTCOMMITTER_ALGORITHM_VERSION_DEFAULT
static String	FILEOUTPUTCOMMITTER_FAILURE_ATTEMPTS
static int	FILEOUTPUTCOMMITTER_FAILURE_ATTEMPTS_DEFAULT
static String	PENDING_DIR_NAME Name of directory where pending data is placed.
static String	SUCCEEDED_FILE_NAME
static String	SUCCESSFUL_JOB_OUTPUT_DIR_MARKER
protected static String	TEMP_DIR_NAME Deprecated.

Constructor Summary

Constructors

Constructor and Description
FileOutputCommitter(Path outputPath, JobContext context) Create a file output committer
FileOutputCommitter(Path outputPath, TaskAttemptContext context) Create a file output committer

Method Summary

Methods

Modifier and Type	Method and Description
void	abortJob(JobContext context, org.apache.hadoop.mapreduce.JobStatus.State state) Delete the temporary directory, including all of the work directories.
void	abortTask(TaskAttemptContext context) Delete the work directory
void	cleanupJob(JobContext context) Deprecated.
void	commitJob(JobContext context) The job has completed, so do works in commitJobInternal().
protected void	commitJobInternal(JobContext context) The job has completed, so do following commit job, include: Move all committed tasks to the final output dir (algorithm 1 only).
void	commitTask(TaskAttemptContext context) Move the files from the work directory to the job output directory
protected Path	getCommittedTaskPath(int appAttemptId, TaskAttemptContext context) Compute the path where the output of a committed task is stored until the entire job is committed for a specific application attempt.
Path	getCommittedTaskPath(TaskAttemptContext context) Compute the path where the output of a committed task is stored until the entire job is committed.
static Path	getCommittedTaskPath(TaskAttemptContext context, Path out)
protected Path	getJobAttemptPath(int appAttemptId) Compute the path where the output of a given job attempt will be placed.
Path	getJobAttemptPath(JobContext context) Compute the path where the output of a given job attempt will be placed.
static Path	getJobAttemptPath(JobContext context, Path out) Compute the path where the output of a given job attempt will be placed.
Path	getTaskAttemptPath(TaskAttemptContext context) Compute the path where the output of a task attempt is stored until that task is committed.
static Path	getTaskAttemptPath(TaskAttemptContext context, Path out) Compute the path where the output of a task attempt is stored until that task is committed.
Path	getWorkPath() Get the directory that the task should write results into.
boolean	isCommitJobRepeatable(JobContext context) Returns true if an in-progress job commit can be retried.
boolean	isRecoverySupported() Deprecated.
boolean	needsTaskCommit(TaskAttemptContext context) Did this task write any files in the work directory?
void	recoverTask(TaskAttemptContext context) Recover the task output.
void	setupJob(JobContext context) Create the temporary directory that is the root of all of the task work directories.
void	setupTask(TaskAttemptContext context) No task setup required.

Methods inherited from class org.apache.hadoop.mapreduce.OutputCommitter

isRecoverySupported

Methods inherited from class java.lang.Object

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

Field Detail

PENDING_DIR_NAME

public static final String PENDING_DIR_NAME

Name of directory where pending data is placed. Data that has not been committed yet.

See Also:

Constant Field Values

TEMP_DIR_NAME

@Deprecated
protected static final String TEMP_DIR_NAME

Deprecated.

Temporary directory name The static variable to be compatible with M/R 1.x

See Also:

Constant Field Values

SUCCEEDED_FILE_NAME

public static final String SUCCEEDED_FILE_NAME

See Also:

Constant Field Values

SUCCESSFUL_JOB_OUTPUT_DIR_MARKER

public static final String SUCCESSFUL_JOB_OUTPUT_DIR_MARKER

See Also:

Constant Field Values

FILEOUTPUTCOMMITTER_ALGORITHM_VERSION

public static final String FILEOUTPUTCOMMITTER_ALGORITHM_VERSION

See Also:

Constant Field Values

FILEOUTPUTCOMMITTER_ALGORITHM_VERSION_DEFAULT

public static final int FILEOUTPUTCOMMITTER_ALGORITHM_VERSION_DEFAULT

See Also:

Constant Field Values

FILEOUTPUTCOMMITTER_FAILURE_ATTEMPTS

public static final String FILEOUTPUTCOMMITTER_FAILURE_ATTEMPTS

See Also:

Constant Field Values

FILEOUTPUTCOMMITTER_FAILURE_ATTEMPTS_DEFAULT

public static final int FILEOUTPUTCOMMITTER_FAILURE_ATTEMPTS_DEFAULT

See Also:

Constant Field Values

Constructor Detail

FileOutputCommitter

public FileOutputCommitter(Path outputPath,
                   TaskAttemptContext context)
                    throws IOException

Create a file output committer

Parameters:

outputPath - the job's output path, or null if you want the output committer to act as a noop.

context - the task's context

Throws:

IOException

FileOutputCommitter

@InterfaceAudience.Private
public FileOutputCommitter(Path outputPath,
                                             JobContext context)
                    throws IOException

Create a file output committer

Parameters:

outputPath - the job's output path, or null if you want the output committer to act as a noop.

context - the task's context

Throws:

IOException

Method Detail

getJobAttemptPath

public Path getJobAttemptPath(JobContext context)

Compute the path where the output of a given job attempt will be placed.

Parameters:

context - the context of the job. This is used to get the application attempt id.

Returns:

the path to store job attempt data.

getJobAttemptPath

public static Path getJobAttemptPath(JobContext context,
                     Path out)

Compute the path where the output of a given job attempt will be placed.

Parameters:

context - the context of the job. This is used to get the application attempt id.

out - the output path to place these in.

Returns:

the path to store job attempt data.

getJobAttemptPath

protected Path getJobAttemptPath(int appAttemptId)

Compute the path where the output of a given job attempt will be placed.

Parameters:

appAttemptId - the ID of the application attempt for this job.

Returns:

the path to store job attempt data.

getTaskAttemptPath

public Path getTaskAttemptPath(TaskAttemptContext context)

Compute the path where the output of a task attempt is stored until that task is committed.

Parameters:

context - the context of the task attempt.

Returns:

the path where a task attempt should be stored.

getTaskAttemptPath

public static Path getTaskAttemptPath(TaskAttemptContext context,
                      Path out)

Compute the path where the output of a task attempt is stored until that task is committed.

Parameters:

context - the context of the task attempt.

out - The output path to put things in.

Returns:

the path where a task attempt should be stored.

getCommittedTaskPath

public Path getCommittedTaskPath(TaskAttemptContext context)

Compute the path where the output of a committed task is stored until the entire job is committed.

Parameters:

context - the context of the task attempt

Returns:

the path where the output of a committed task is stored until the entire job is committed.

getCommittedTaskPath

public static Path getCommittedTaskPath(TaskAttemptContext context,
                        Path out)

getCommittedTaskPath

protected Path getCommittedTaskPath(int appAttemptId,
                        TaskAttemptContext context)

Compute the path where the output of a committed task is stored until the entire job is committed for a specific application attempt.

Parameters:

appAttemptId - the id of the application attempt to use

context - the context of any task.

Returns:

the path where the output of a committed task is stored.

getWorkPath

public Path getWorkPath()
                 throws IOException

Get the directory that the task should write results into.

Returns:

the work directory

Throws:

IOException

setupJob

public void setupJob(JobContext context)
              throws IOException

Create the temporary directory that is the root of all of the task work directories.

Specified by:

setupJob in class OutputCommitter

Parameters:

context - the job's context

Throws:

IOException - if temporary output could not be created

commitJob

public void commitJob(JobContext context)
               throws IOException

The job has completed, so do works in commitJobInternal(). Could retry on failure if using algorithm 2.

Overrides:

commitJob in class OutputCommitter

Parameters:

context - the job's context

Throws:

IOException

commitJobInternal

protected void commitJobInternal(JobContext context)
                          throws IOException

The job has completed, so do following commit job, include: Move all committed tasks to the final output dir (algorithm 1 only). Delete the temporary directory, including all of the work directories. Create a _SUCCESS file to make it as successful.

Parameters:

context - the job's context

Throws:

IOException

cleanupJob

@Deprecated
public void cleanupJob(JobContext context)
                throws IOException

Deprecated.

Description copied from class: OutputCommitter

For cleaning up the job's output after job completion. This is called from the application master process for the entire job. This may be called multiple times.

Overrides:

cleanupJob in class OutputCommitter

Parameters:

context - Context of the job whose output is being written.

Throws:

IOException

abortJob

public void abortJob(JobContext context,
            org.apache.hadoop.mapreduce.JobStatus.State state)
              throws IOException

Delete the temporary directory, including all of the work directories.

Overrides:

abortJob in class OutputCommitter

Parameters:

context - the job's context

state - final runstate of the job

Throws:

IOException

setupTask

public void setupTask(TaskAttemptContext context)
               throws IOException

No task setup required.

Specified by:

setupTask in class OutputCommitter

Parameters:

context - Context of the task whose output is being written.

Throws:

IOException

commitTask

public void commitTask(TaskAttemptContext context)
                throws IOException

Move the files from the work directory to the job output directory

Specified by:

commitTask in class OutputCommitter

Parameters:

context - the task context

Throws:

IOException - if commit is not successful.

abortTask

public void abortTask(TaskAttemptContext context)
               throws IOException

Delete the work directory

Specified by:

abortTask in class OutputCommitter

Throws:

IOException

needsTaskCommit

public boolean needsTaskCommit(TaskAttemptContext context)
                        throws IOException

Did this task write any files in the work directory?

Specified by:

needsTaskCommit in class OutputCommitter

Parameters:

context - the task's context

Returns:

true/false

Throws:

IOException

isRecoverySupported

@Deprecated
public boolean isRecoverySupported()

Deprecated.

Description copied from class: OutputCommitter

Is task output recovery supported for restarting jobs? If task output recovery is supported, job restart can be done more efficiently.

Overrides:

isRecoverySupported in class OutputCommitter

Returns:

true if task output recovery is supported, false otherwise

See Also:

OutputCommitter.recoverTask(TaskAttemptContext)

isCommitJobRepeatable

public boolean isCommitJobRepeatable(JobContext context)
                              throws IOException

Description copied from class: OutputCommitter

Returns true if an in-progress job commit can be retried. If the MR AM is re-run then it will check this value to determine if it can retry an in-progress commit that was started by a previous version. Note that in rare scenarios, the previous AM version might still be running at that time, due to system anomalies. Hence if this method returns true then the retry commit operation should be able to run concurrently with the previous operation. If repeatable job commit is supported, job restart can tolerate previous AM failures during job commit. By default, it is not supported. Extended classes (like: FileOutputCommitter) should explicitly override it if provide support.

Overrides:

isCommitJobRepeatable in class OutputCommitter

Parameters:

context - Context of the job whose output is being written.

Returns:

true repeatable job commit is supported, false otherwise

Throws:

IOException

recoverTask

public void recoverTask(TaskAttemptContext context)
                 throws IOException

Description copied from class: OutputCommitter

Recover the task output. The retry-count for the job will be passed via the MRJobConfig.APPLICATION_ATTEMPT_ID key in JobContext.getConfiguration() for the OutputCommitter. This is called from the application master process, but it is called individually for each task. If an exception is thrown the task will be attempted again. This may be called multiple times for the same task. But from different application attempts.

Overrides:

recoverTask in class OutputCommitter

Parameters:

context - Context of the task whose output is being recovered

Throws:

IOException