org.apache.spark.internal.io

Class HadoopMapReduceCommitProtocol

Object

org.apache.spark.internal.io.FileCommitProtocol

org.apache.spark.internal.io.HadoopMapReduceCommitProtocol

All Implemented Interfaces:

java.io.Serializable

public class HadoopMapReduceCommitProtocol
extends FileCommitProtocol
implements scala.Serializable

An FileCommitProtocol implementation backed by an underlying Hadoop OutputCommitter (from the newer mapreduce API, not the old mapred API).

Unlike Hadoop's OutputCommitter, this implementation is serializable.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.spark.internal.io.FileCommitProtocol

FileCommitProtocol.EmptyTaskCommitMessage$, FileCommitProtocol.TaskCommitMessage

Constructor Summary

Constructors

Constructor and Description
HadoopMapReduceCommitProtocol(String jobId, String path)

Method Summary

Methods

Modifier and Type	Method and Description
void	abortJob(org.apache.hadoop.mapreduce.JobContext jobContext) Aborts a job after the writes fail.
void	abortTask(org.apache.hadoop.mapreduce.TaskAttemptContext taskContext) Aborts a task after the writes have failed.
void	commitJob(org.apache.hadoop.mapreduce.JobContext jobContext, scala.collection.Seq<FileCommitProtocol.TaskCommitMessage> taskCommits) Commits a job after the writes succeed.
FileCommitProtocol.TaskCommitMessage	commitTask(org.apache.hadoop.mapreduce.TaskAttemptContext taskContext) Commits a task after the writes succeed.
String	newTaskTempFile(org.apache.hadoop.mapreduce.TaskAttemptContext taskContext, scala.Option<String> dir, String ext) Notifies the commit protocol to add a new file, and gets back the full path that should be used.
String	newTaskTempFileAbsPath(org.apache.hadoop.mapreduce.TaskAttemptContext taskContext, String absoluteDir, String ext) Similar to newTaskTempFile(), but allows files to committed to an absolute output location.
void	setupJob(org.apache.hadoop.mapreduce.JobContext jobContext) Setups up a job.
void	setupTask(org.apache.hadoop.mapreduce.TaskAttemptContext taskContext) Sets up a task within a job.

Methods inherited from class org.apache.spark.internal.io.FileCommitProtocol

instantiate

Methods inherited from class Object

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

Constructor Detail

HadoopMapReduceCommitProtocol

public HadoopMapReduceCommitProtocol(String jobId,
                             String path)

Method Detail

newTaskTempFile

public String newTaskTempFile(org.apache.hadoop.mapreduce.TaskAttemptContext taskContext,
                     scala.Option<String> dir,
                     String ext)

Description copied from class: FileCommitProtocol

Notifies the commit protocol to add a new file, and gets back the full path that should be used. Must be called on the executors when running tasks.

Note that the returned temp file may have an arbitrary path. The commit protocol only promises that the file will be at the location specified by the arguments after job commit.

A full file path consists of the following parts: 1. the base path 2. some sub-directory within the base path, used to specify partitioning 3. file prefix, usually some unique job id with the task id 4. bucket id 5. source specific file extension, e.g. ".snappy.parquet"

The "dir" parameter specifies 2, and "ext" parameter specifies both 4 and 5, and the rest are left to the commit protocol implementation to decide.

Important: it is the caller's responsibility to add uniquely identifying content to "ext" if a task is going to write out multiple files to the same dir. The file commit protocol only guarantees that files written by different tasks will not conflict.

Specified by:

newTaskTempFile in class FileCommitProtocol

Parameters:

taskContext - (undocumented)

dir - (undocumented)

ext - (undocumented)

Returns:

(undocumented)

newTaskTempFileAbsPath

public String newTaskTempFileAbsPath(org.apache.hadoop.mapreduce.TaskAttemptContext taskContext,
                            String absoluteDir,
                            String ext)

Description copied from class: FileCommitProtocol

Similar to newTaskTempFile(), but allows files to committed to an absolute output location. Depending on the implementation, there may be weaker guarantees around adding files this way.

Important: it is the caller's responsibility to add uniquely identifying content to "ext" if a task is going to write out multiple files to the same dir. The file commit protocol only guarantees that files written by different tasks will not conflict.

Specified by:

newTaskTempFileAbsPath in class FileCommitProtocol

Parameters:

taskContext - (undocumented)

absoluteDir - (undocumented)

ext - (undocumented)

Returns:

(undocumented)

setupJob

public void setupJob(org.apache.hadoop.mapreduce.JobContext jobContext)

Description copied from class: FileCommitProtocol

Setups up a job. Must be called on the driver before any other methods can be invoked.

Specified by:

setupJob in class FileCommitProtocol

Parameters:

jobContext - (undocumented)

commitJob

public void commitJob(org.apache.hadoop.mapreduce.JobContext jobContext,
             scala.collection.Seq<FileCommitProtocol.TaskCommitMessage> taskCommits)

Description copied from class: FileCommitProtocol

Commits a job after the writes succeed. Must be called on the driver.

Specified by:

commitJob in class FileCommitProtocol

Parameters:

jobContext - (undocumented)

taskCommits - (undocumented)

abortJob

public void abortJob(org.apache.hadoop.mapreduce.JobContext jobContext)

Description copied from class: FileCommitProtocol

Aborts a job after the writes fail. Must be called on the driver.

Calling this function is a best-effort attempt, because it is possible that the driver just crashes (or killed) before it can call abort.

Specified by:

abortJob in class FileCommitProtocol

Parameters:

jobContext - (undocumented)

setupTask

public void setupTask(org.apache.hadoop.mapreduce.TaskAttemptContext taskContext)

Description copied from class: FileCommitProtocol

Sets up a task within a job. Must be called before any other task related methods can be invoked.

Specified by:

setupTask in class FileCommitProtocol

Parameters:

taskContext - (undocumented)

commitTask

public FileCommitProtocol.TaskCommitMessage commitTask(org.apache.hadoop.mapreduce.TaskAttemptContext taskContext)

Description copied from class: FileCommitProtocol

Commits a task after the writes succeed. Must be called on the executors when running tasks.

Specified by:

commitTask in class FileCommitProtocol

Parameters:

taskContext - (undocumented)

Returns:

(undocumented)

abortTask

public void abortTask(org.apache.hadoop.mapreduce.TaskAttemptContext taskContext)

Description copied from class: FileCommitProtocol

Aborts a task after the writes have failed. Must be called on the executors when running tasks.

Calling this function is a best-effort attempt, because it is possible that the executor just crashes (or killed) before it can call abort.

Specified by:

abortTask in class FileCommitProtocol

Parameters:

taskContext - (undocumented)