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From "Samuel Guo" <guosi...@gmail.com>
Subject Re: NullPointerException at AbstractVector.get(AbstractVector.java:44)
Date Thu, 04 Dec 2008 14:30:45 GMT
what is the matrix's size?
what is the block's size?
can the matrix's size be interge-divided by block's size?
if not, the last sub-vector's index range will be out of bound.

so, the get() method in AbstractVector will get *Null* when calling
*this.entries.get(index)*. The code is as below.

public double get(int index) throws NullPointerException {
    return this.entries.get(index).getValue();
}

It is a bug. A Jira may be filed to fix two files of the code.

first:
Method *setBlockPosition* in DenseMatrix class;
second:
Class *BlockingMapper* in BlockingMapRed class;

I am sorry. :-(
I have found the potential bug in DenseMatrix when I write the
BlockingMapRed class. But I forget to fix it and use the same way to
caculate the block ranges during mapping.

On Thu, Dec 4, 2008 at 3:09 PM, Edward J. Yoon <edwardyoon@apache.org>wrote:

> Can someone figure out this problem?
>
> 08/12/04 15:58:37 INFO hama.AbstractMatrix: Convert to 20 * 20 blocked
> matrix
> 08/12/04 15:58:37 WARN mapred.JobClient: Use GenericOptionsParser for
> parsing the arguments. Applications should implement Tool for the
> same.
> 08/12/04 15:58:37 WARN mapred.JobClient: Use genericOptions for the
> option -libjars
> 08/12/04 15:58:38 WARN mapred.JobClient: No job jar file set.  User
> classes may not be found. See JobConf(Class) or
> JobConf#setJar(String).
> 08/12/04 15:58:38 INFO mapred.JobClient: Running job: job_200812041310_0026
> 08/12/04 15:58:39 INFO mapred.JobClient:  map 0% reduce 0%
> 08/12/04 15:59:29 INFO mapred.JobClient: Task Id :
> attempt_200812041310_0026_m_000002_0, Status : FAILED
> java.lang.NullPointerException: v(1) : java.lang.NullPointerException
>        at org.apache.hama.AbstractVector.get(AbstractVector.java:44)
>        at org.apache.hama.DenseVector.subVector(DenseVector.java:151)
>        at
> org.apache.hama.mapred.BlockingMapRed$BlockingMapper.map(BlockingMapRed.java:112)
>        at
> org.apache.hama.mapred.BlockingMapRed$BlockingMapper.map(BlockingMapRed.java:98)
>        at org.apache.hadoop.mapred.MapRunner.run(MapRunner.java:47)
>        at org.apache.hadoop.mapred.MapTask.run(MapTask.java:227)
>        at
> org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:2207)
> --
> Best Regards, Edward J. Yoon @ NHN, corp.
> edwardyoon@apache.org
> http://blog.udanax.org
>

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