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java.lang.Objectorg.apache.hadoop.mapreduce.Mapper<ImmutableBytesWritable,Result,KEYOUT,VALUEOUT>
org.apache.hadoop.hbase.mapreduce.TableMapper<K2,V2>
org.apache.hadoop.hbase.mapreduce.MultithreadedTableMapper<K2,V2>
public class MultithreadedTableMapper<K2,V2>
Multithreaded implementation for @link org.apache.hbase.mapreduce.TableMapper
It can be used instead when the Map operation is not CPU bound in order to improve throughput.
Mapper implementations using this MapRunnable must be thread-safe.
The Map-Reduce job has to be configured with the mapper to use via
#setMapperClass(Configuration, Class)
and
the number of thread the thread-pool can use with the
{@link #getNumberOfThreads(Configuration) method. The default
value is 10 threads.
Nested Class Summary |
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Nested classes/interfaces inherited from class org.apache.hadoop.mapreduce.Mapper |
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org.apache.hadoop.mapreduce.Mapper.Context |
Field Summary | |
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static String |
MAPPER_CLASS
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static String |
NUMBER_OF_THREADS
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Constructor Summary | |
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MultithreadedTableMapper()
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Method Summary | ||
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static
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getMapperClass(org.apache.hadoop.mapreduce.JobContext job)
Get the application's mapper class. |
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static int |
getNumberOfThreads(org.apache.hadoop.mapreduce.JobContext job)
The number of threads in the thread pool that will run the map function. |
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void |
run(org.apache.hadoop.mapreduce.Mapper.Context context)
Run the application's maps using a thread pool. |
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static
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setMapperClass(org.apache.hadoop.mapreduce.Job job,
Class<? extends org.apache.hadoop.mapreduce.Mapper<ImmutableBytesWritable,Result,K2,V2>> cls)
Set the application's mapper class. |
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static void |
setNumberOfThreads(org.apache.hadoop.mapreduce.Job job,
int threads)
Set the number of threads in the pool for running maps. |
Methods inherited from class org.apache.hadoop.mapreduce.Mapper |
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cleanup, map, setup |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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public static final String NUMBER_OF_THREADS
public static final String MAPPER_CLASS
Constructor Detail |
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public MultithreadedTableMapper()
Method Detail |
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public static int getNumberOfThreads(org.apache.hadoop.mapreduce.JobContext job)
job
- the job
public static void setNumberOfThreads(org.apache.hadoop.mapreduce.Job job, int threads)
job
- the job to modifythreads
- the new number of threadspublic static <K2,V2> Class<org.apache.hadoop.mapreduce.Mapper<ImmutableBytesWritable,Result,K2,V2>> getMapperClass(org.apache.hadoop.mapreduce.JobContext job)
K2
- the map's output key typeV2
- the map's output value typejob
- the job
public static <K2,V2> void setMapperClass(org.apache.hadoop.mapreduce.Job job, Class<? extends org.apache.hadoop.mapreduce.Mapper<ImmutableBytesWritable,Result,K2,V2>> cls)
K2
- the map output key typeV2
- the map output value typejob
- the job to modifycls
- the class to use as the mapperpublic void run(org.apache.hadoop.mapreduce.Mapper.Context context) throws IOException, InterruptedException
run
in class org.apache.hadoop.mapreduce.Mapper<ImmutableBytesWritable,Result,K2,V2>
IOException
InterruptedException
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