public class DelegatingMapper<K1,V1,K2,V2> extends java.lang.Object implements Mapper<K1,V1,K2,V2>
Mapper
that delegates behaviour of paths to multiple other
mappers.Constructor and Description |
---|
DelegatingMapper() |
Modifier and Type | Method and Description |
---|---|
void |
close() |
void |
configure(JobConf conf)
Initializes a new instance from a
JobConf . |
void |
map(K1 key,
V1 value,
OutputCollector<K2,V2> outputCollector,
Reporter reporter)
Maps a single input key/value pair into an intermediate key/value pair.
|
public void map(K1 key, V1 value, OutputCollector<K2,V2> outputCollector, Reporter reporter) throws java.io.IOException
Mapper
Output pairs need not be of the same types as input pairs. A given
input pair may map to zero or many output pairs. Output pairs are
collected with calls to
OutputCollector.collect(Object,Object)
.
Applications can use the Reporter
provided to report progress
or just indicate that they are alive. In scenarios where the application
takes an insignificant amount of time to process individual key/value
pairs, this is crucial since the framework might assume that the task has
timed-out and kill that task. The other way of avoiding this is to set
mapred.task.timeout to a high-enough value (or even zero for no
time-outs).
public void configure(JobConf conf)
JobConfigurable
JobConf
.configure
in interface JobConfigurable
conf
- the configurationpublic void close() throws java.io.IOException
close
in interface java.io.Closeable
close
in interface java.lang.AutoCloseable
java.io.IOException
Copyright © 2009 The Apache Software Foundation