@InterfaceAudience.Public @InterfaceStability.Stable public class MultithreadedMapRunner<K1,V1,K2,V2> extends Object implements MapRunnable<K1,V1,K2,V2>
MapRunnable
.
It can be used instead of the default implementation,
of MapRunner
, when the Map
operation is not CPU bound in order to improve throughput.
Map implementations using this MapRunnable must be thread-safe.
The Map-Reduce job has to be configured to use this MapRunnable class (using
the JobConf.setMapRunnerClass method) and
the number of threads the thread-pool can use with the
mapred.map.multithreadedrunner.threads
property, its default
value is 10 threads.
Constructor and Description |
---|
MultithreadedMapRunner() |
Modifier and Type | Method and Description |
---|---|
void |
configure(JobConf jobConf)
Initializes a new instance from a
JobConf . |
void |
run(RecordReader<K1,V1> input,
OutputCollector<K2,V2> output,
Reporter reporter)
Start mapping input
<key, value> pairs. |
public void configure(JobConf jobConf)
JobConfigurable
JobConf
.configure
in interface JobConfigurable
jobConf
- the configurationpublic void run(RecordReader<K1,V1> input, OutputCollector<K2,V2> output, Reporter reporter) throws IOException
MapRunnable
<key, value>
pairs.
Mapping of input records to output records is complete when this method returns.
run
in interface MapRunnable<K1,V1,K2,V2>
input
- the RecordReader
to read the input records.output
- the OutputCollector
to collect the outputrecords.reporter
- Reporter
to report progress, status-updates etc.IOException
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