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From Ted Yu <yuzhih...@gmail.com>
Subject Re: User defined class as Map/Reduce output value
Date Wed, 28 Apr 2010 01:13:20 GMT
Can you try adding 'org.apache.hadoop.io.serializer.JavaSerialization,' to
the following config ?
"C:\hadoop-0.20.2\src\core\core-default.xml"(87,9):
  <name>io.serializations</name>

By default, only org.apache.hadoop.io.serializer.WritableSerialization is
included.

On Tue, Apr 27, 2010 at 3:55 PM, Farhan Husain <farhan.husain@csebuet.org>wrote:

> I tried to use a class which implements the Serializable interface and got
> the following error:
>
> java.lang.NullPointerException
>    at
>
> org.apache.hadoop.io.serializer.SerializationFactory.getSerializer(SerializationFactory.java:73)
>    at
> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.<init>(MapTask.java:759)
>    at
>
> org.apache.hadoop.mapred.MapTask$NewOutputCollector.<init>(MapTask.java:487)
>    at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:575)
>    at org.apache.hadoop.mapred.MapTask.run(MapTask.java:305)
>    at org.apache.hadoop.mapred.Child.main(Child.java:170)
>
> On Tue, Apr 27, 2010 at 12:53 PM, Farhan Husain
> <farhan.husain@csebuet.org>wrote:
>
> > Hello,
> >
> > I want to output a class which I have written as the value of the map
> > phase. The obvious was is to implement the Writable interface but the
> > problem is the class has other classes as its member properties. The
> > DataInput and DataOutput interfaces used by the read and write methods of
> > the Writable class do not support object serialization. Is there any
> other
> > way I can achieve this?
> >
> > Thanks,
> > Farhan
> >
>

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