@InterfaceAudience.Private @InterfaceStability.Unstable public class DelegatingMapper<K1,V1,K2,V2> extends 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 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 significant 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
mapreduce.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 IOException
close
in interface Closeable
close
in interface AutoCloseable
IOException
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