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java.lang.Objectorg.apache.hadoop.streaming.PipeMapRed
org.apache.hadoop.streaming.PipeMapper
public class PipeMapper
A generic Mapper bridge. It delegates operations to an external program via stdin and stdout.
| Field Summary |
|---|
| Fields inherited from class org.apache.hadoop.streaming.PipeMapRed |
|---|
LOG, outerrThreadsThrowable |
| Constructor Summary | |
|---|---|
PipeMapper()
|
|
| Method Summary | |
|---|---|
void |
close()
|
void |
configure(JobConf job)
Initializes a new instance from a JobConf. |
byte[] |
getFieldSeparator()
Returns the field separator to be used. |
byte[] |
getInputSeparator()
Returns the input separator to be used. |
int |
getNumOfKeyFields()
Returns the number of key fields. |
void |
map(Object key,
Object value,
OutputCollector output,
Reporter reporter)
Maps a single input key/value pair into an intermediate key/value pair. |
| Methods inherited from class org.apache.hadoop.streaming.PipeMapRed |
|---|
getClientInput, getClientOutput, getConfiguration, getContext, mapRedFinished |
| Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Constructor Detail |
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public PipeMapper()
| Method Detail |
|---|
public void configure(JobConf job)
JobConfigurableJobConf.
configure in interface JobConfigurableconfigure in class PipeMapRedjob - the configuration
public void map(Object key,
Object value,
OutputCollector output,
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 Mapperkey - the input key.value - the input value.output - collects mapped keys and values.reporter - facility to report progress.
IOExceptionpublic void close()
close in interface Closeablepublic byte[] getInputSeparator()
PipeMapRed
getInputSeparator in class PipeMapRedpublic byte[] getFieldSeparator()
PipeMapRed
getFieldSeparator in class PipeMapRedpublic int getNumOfKeyFields()
PipeMapRed
getNumOfKeyFields in class PipeMapRed
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