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https://issues.apache.org/jira/browse/HDFS-7678?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14531718#comment-14531718
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Zhe Zhang commented on HDFS-7678:
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bq. I think to make the test simple, we can use end-to-end tests like
TestDFSStripedInputStream.
End-to-end testing is indeed simpler; in order to fake a striped file we have
to add a considerable chunk of new code (metadata first, then fake blocks on
DN). But I think it's worth it because it makes the test faster, and also more
accurately test the input stream logic. The content-dismatch failures are
pretty hard to debug if we go through all levels (writing, codec); I just spent
several good hours to find out the above test failure is a codec level issue :(
Once we have this isolated test ready we don't need to worry about future bugs
in output stream and codec.
> Erasure coding: DFSInputStream with decode functionality (pread)
> ----------------------------------------------------------------
>
> Key: HDFS-7678
> URL: https://issues.apache.org/jira/browse/HDFS-7678
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Affects Versions: HDFS-7285
> Reporter: Li Bo
> Assignee: Zhe Zhang
> Attachments: BlockGroupReader.patch, HDFS-7678-HDFS-7285.002.patch,
> HDFS-7678-HDFS-7285.003.patch, HDFS-7678-HDFS-7285.004.patch,
> HDFS-7678-HDFS-7285.005.patch, HDFS-7678-HDFS-7285.006.patch,
> HDFS-7678-HDFS-7285.007.patch, HDFS-7678-HDFS-7285.008.patch,
> HDFS-7678-HDFS-7285.009.patch, HDFS-7678-HDFS-7285.010.patch,
> HDFS-7678.000.patch, HDFS-7678.001.patch
>
>
> A block group reader will read data from BlockGroup no matter in striping
> layout or contiguous layout. The corrupt blocks can be known before
> reading(told by namenode), or just be found during reading. The block group
> reader needs to do decoding work when some blocks are found corrupt.
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