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java.lang.Objectorg.apache.hadoop.mapred.lib.DelegatingMapper<K1,V1,K2,V2>
public class DelegatingMapper<K1,V1,K2,V2>
An Mapper that delegates behaviour of paths to multiple other
mappers.
MultipleInputs.addInputPath(JobConf, Path, Class, Class)| Constructor Summary | |
|---|---|
DelegatingMapper()
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| Method Summary | |
|---|---|
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. |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Constructor Detail |
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public DelegatingMapper()
| Method Detail |
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public void map(K1 key,
V1 value,
OutputCollector<K2,V2> outputCollector,
Reporter reporter)
throws IOException
MapperOutput 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).
map in interface Mapper<K1,V1,K2,V2>key - the input key.value - the input value.outputCollector - collects mapped keys and values.reporter - facility to report progress.
IOExceptionpublic void configure(JobConf conf)
JobConfigurableJobConf.
configure in interface JobConfigurableconf - the configuration
public void close()
throws IOException
close in interface CloseableIOException
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