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https://issues.apache.org/jira/browse/SYSTEMML-1762?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16084943#comment-16084943
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Mike Dusenberry commented on SYSTEMML-1762:
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cc [~mboehm7]
> Improve the robustness of sparse matrix reshape function for the Spark mode
> ---------------------------------------------------------------------------
>
> Key: SYSTEMML-1762
> URL: https://issues.apache.org/jira/browse/SYSTEMML-1762
> Project: SystemML
> Issue Type: Bug
> Components: Algorithms, ParFor, Runtime
> Reporter: Fei Hu
> Assignee: Fei Hu
> Attachments: MNIST_Distrib_Sgd.scala
>
>
> When running the [distributed MNIST LeNet example |
> https://github.com/apache/systemml/blob/master/scripts/nn/examples/mnist_lenet_distrib_sgd.dml],
> it works well in the hybrid mode. But in the Spark mode, there is a
> {{java.lang.NullPointerException}} error when reshaping the sparse matrix.
> The involved function is
> {{org.apache.sysml.runtime.matrix.data.LibMatrixReorg#reshapeSparse}} . The
> reason is that the output matrix index computed by
> {{org.apache.sysml.runtime.matrix.data.LibMatrixReorg#computeResultBlockIndex}}
> does not exist in the {{HashMap<MatrixIndexes,MatrixBlock> rix}}.
> To reproduce the error, the attached scala file {{MNIST_Distrib_Sgd.scala}}
> could be used to run the distributed MNIST example.
> In addition, if adding some codes to ignore the null output matrix block from
> {{MatrixBlock out = rix.get(ixtmp)}}, the distributed MNIST example could
> run in the Spark mode, but the result may not be right.
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