org.apache.hadoop.mapreduce.lib.input

类 CombineFileInputFormat<K,V>

java.lang.Object

org.apache.hadoop.mapreduce.InputFormat<K,V>

org.apache.hadoop.mapreduce.lib.input.FileInputFormat<K,V>

org.apache.hadoop.mapreduce.lib.input.CombineFileInputFormat<K,V>

@InterfaceAudience.Public
@InterfaceStability.Stable
public abstract class CombineFileInputFormat<K,V>
extends FileInputFormat<K,V>

An abstract InputFormat that returns CombineFileSplit's in InputFormat.getSplits(JobContext) method. Splits are constructed from the files under the input paths. A split cannot have files from different pools. Each split returned may contain blocks from different files. If a maxSplitSize is specified, then blocks on the same node are combined to form a single split. Blocks that are left over are then combined with other blocks in the same rack. If maxSplitSize is not specified, then blocks from the same rack are combined in a single split; no attempt is made to create node-local splits. If the maxSplitSize is equal to the block size, then this class is similar to the default splitting behavior in Hadoop: each block is a locally processed split. Subclasses implement InputFormat.createRecordReader(InputSplit, TaskAttemptContext) to construct RecordReader's for CombineFileSplit's.

另请参阅:

CombineFileSplit

嵌套类概要

从类继承的嵌套类/接口 org.apache.hadoop.mapreduce.lib.input.FileInputFormat

FileInputFormat.Counter

字段概要

字段

限定符和类型	字段和说明
static String	SPLIT_MINSIZE_PERNODE
static String	SPLIT_MINSIZE_PERRACK

构造器概要

构造器

构造器和说明
CombineFileInputFormat() default constructor

方法概要

方法

限定符和类型	方法和说明
protected void	createPool(List<PathFilter> filters) Create a new pool and add the filters to it.
protected void	createPool(PathFilter... filters) Create a new pool and add the filters to it.
abstract RecordReader<K,V>	createRecordReader(InputSplit split, TaskAttemptContext context) This is not implemented yet.
protected BlockLocation[]	getFileBlockLocations(FileSystem fs, FileStatus stat)
List<InputSplit>	getSplits(JobContext job) Generate the list of files and make them into FileSplits.
protected boolean	isSplitable(JobContext context, Path file) Is the given filename splitable?
protected void	setMaxSplitSize(long maxSplitSize) Specify the maximum size (in bytes) of each split.
protected void	setMinSplitSizeNode(long minSplitSizeNode) Specify the minimum size (in bytes) of each split per node.
protected void	setMinSplitSizeRack(long minSplitSizeRack) Specify the minimum size (in bytes) of each split per rack.

从类继承的方法 org.apache.hadoop.mapreduce.lib.input.FileInputFormat

addInputPath, addInputPaths, computeSplitSize, getBlockIndex, getFormatMinSplitSize, getInputPathFilter, getInputPaths, getMaxSplitSize, getMinSplitSize, listStatus, setInputPathFilter, setInputPaths, setInputPaths, setMaxInputSplitSize, setMinInputSplitSize

从类继承的方法 java.lang.Object

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

字段详细资料

SPLIT_MINSIZE_PERNODE

public static final String SPLIT_MINSIZE_PERNODE

另请参阅:

常量字段值

SPLIT_MINSIZE_PERRACK

public static final String SPLIT_MINSIZE_PERRACK

另请参阅:

常量字段值

构造器详细资料

CombineFileInputFormat

public CombineFileInputFormat()

default constructor

方法详细资料

setMaxSplitSize

protected void setMaxSplitSize(long maxSplitSize)

Specify the maximum size (in bytes) of each split. Each split is approximately equal to the specified size.

setMinSplitSizeNode

protected void setMinSplitSizeNode(long minSplitSizeNode)

Specify the minimum size (in bytes) of each split per node. This applies to data that is left over after combining data on a single node into splits that are of maximum size specified by maxSplitSize. This leftover data will be combined into its own split if its size exceeds minSplitSizeNode.

setMinSplitSizeRack

protected void setMinSplitSizeRack(long minSplitSizeRack)

Specify the minimum size (in bytes) of each split per rack. This applies to data that is left over after combining data on a single rack into splits that are of maximum size specified by maxSplitSize. This leftover data will be combined into its own split if its size exceeds minSplitSizeRack.

createPool

protected void createPool(List<PathFilter> filters)

Create a new pool and add the filters to it. A split cannot have files from different pools.

createPool

protected void createPool(PathFilter... filters)

Create a new pool and add the filters to it. A pathname can satisfy any one of the specified filters. A split cannot have files from different pools.

isSplitable

protected boolean isSplitable(JobContext context,
                  Path file)

从类复制的说明: FileInputFormat

Is the given filename splitable? Usually, true, but if the file is stream compressed, it will not be. FileInputFormat implementations can override this and return false to ensure that individual input files are never split-up so that Mappers process entire files.

覆盖:

isSplitable 在类中 FileInputFormat<K,V>

参数:

context - the job context

file - the file name to check

返回:

is this file splitable?

getSplits

public List<InputSplit> getSplits(JobContext job)
                           throws IOException

从类复制的说明: FileInputFormat

Generate the list of files and make them into FileSplits.

覆盖:

getSplits 在类中 FileInputFormat<K,V>

参数:

job - job configuration.

返回:

an array of InputSplits for the job.

抛出:

IOException

createRecordReader

public abstract RecordReader<K,V> createRecordReader(InputSplit split,
                                   TaskAttemptContext context)
                                              throws IOException

This is not implemented yet.

指定者:

createRecordReader 在类中 InputFormat<K,V>

参数:

split - the split to be read

context - the information about the task

返回:

a new record reader

抛出:

IOException

getFileBlockLocations

protected BlockLocation[] getFileBlockLocations(FileSystem fs,
                                    FileStatus stat)
                                         throws IOException

抛出:

IOException