From the exception you pasted, it looks like your io.serializations did
not set the SerializationFactory properly. Do you see any logs on your
console for adding serialization class?
Can you try running your app on pseudo distributed mode, instead of
LocalJobRunner ?
You can find pseudo distributed setup at
http://hadoop.apache.org/core/docs/r0.19.0/quickstart.html#PseudoDistributed
Thanks
Amareshwari
Pedro Vivancos wrote:
Dear friends,
I am new at Hadoop and at MapReduce techniques. I've developed my first
map-reduce application using hadoop but I can't manage to make it work. I
get the following error at the very beginning of the execution:
java.lang.NullPointerException
at
org.apache.hadoop.io.serializer.SerializationFactory.getSerializer(SerializationFactory.java:73)
at
org.apache.hadoop.mapred.MapTask$MapOutputBuffer.<init>(MapTask.java:504)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:295)
at
org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:138)
16-ene-2009 18:29:30 es.vocali.intro.tools.memo.MemoAnnotationMerging main
GRAVE: Se ha producido un error
java.io.IOException: Job failed!
at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:1217)
at
es.vocali.intro.tools.memo.MemoAnnotationMerging.main(MemoAnnotationMerging.java:160)
java.io.IOException: Job failed!
at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:1217)
at
es.vocali.intro.tools.memo.MemoAnnotationMerging.main(MemoAnnotationMerging.java:160)
Sorry if I don't give you more information but I don't know where to start
to find the error. My app is quite simple. It just gets some rows from a
postgresql database and try to see which ones can be deleted.
Here you have the configuration I am using:
MemoAnnotationMerging memo = new MemoAnnotationMerging();
Map<String, String> parametros = memo.checkParams(args);
memo.initDataStore(parametros.get(DATASTORE_URL));
JobConf conf = new JobConf(MemoAnnotationMerging.class);
conf.setJobName("memo - annotation merging");
conf.setMapperClass(MemoAnnotationMapper.class);
conf.setCombinerClass(MemoAnnotationReducer.class);
conf.setReducerClass(MemoAnnotationReducer.class);
DBConfiguration.configureDB(conf, DRIVER_CLASS,
parametros.get(DATASTORE_URL));
// ???
//conf.setInputFormat(DBInputFormat.class);
//conf.setOutputFormat(TextOutputFormat.class);
conf.setMapOutputKeyClass(LongWritable.class);
conf.setMapOutputValueClass(Annotation.class);
//conf.setOutputKeyClass(Annotation.class);
//conf.setOutputValueClass(BooleanWritable.class);
DBInputFormat.setInput(conf, MemoAnnotationDBWritable.class,
GET_ANNOTATIONS_QUERY, COUNT_ANNOTATIONS_QUERY);
FileOutputFormat.setOutputPath(conf, new Path("eliminar.txt"));
// ejecutamos el algoritmo map-reduce para mezclar anotaciones
try {
JobClient.runJob(conf);
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
Thanks in advance.
Pedro Vivancos Vicente
Vócali Sistemas Inteligentes S.L. <http://www.vocali.net>
Edificio CEEIM, Campus de Espinardo
30100, Espinardo, Murcia, Spain
Tel. +34 902 929 644 <http://www.vocali.net>
