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https://issues.apache.org/jira/browse/HDFS-11187?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16356540#comment-16356540
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Xiao Chen commented on HDFS-11187:
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Thanks for working on the branch-2 patch Gabor!
I'm not entirely familiar with this part of code, so would be great if
[~jojochuang] or [~kihwal] can double check.
Some review comments:
Agree we should be fine to not port HDFS-10636 (the replicainfo -> file jira)
to branch-2, as Gabor said.
FinalizedReplica.java:
- Should keep the import change (remove fnfe)
- Should remove {{getLastChecksumAndDataLen}}
FsVolumeImpl:
- I think we probably should keep the trunk patch's logic in
{{addFinalizedBlock}}. But given this interface difference, maybe we can move
this to FsDatasetImple, after the {{addFinalizedBlock}} returns and before
creating the {{FinalizedReplica}} object?
> Optimize disk access for last partial chunk checksum of Finalized replica
> -------------------------------------------------------------------------
>
> Key: HDFS-11187
> URL: https://issues.apache.org/jira/browse/HDFS-11187
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: datanode
> Reporter: Wei-Chiu Chuang
> Assignee: Gabor Bota
> Priority: Major
> Fix For: 3.1.0, 3.0.2
>
> Attachments: HDFS-11187-branch-2.001.patch, HDFS-11187.001.patch,
> HDFS-11187.002.patch, HDFS-11187.003.patch, HDFS-11187.004.patch,
> HDFS-11187.005.patch
>
>
> The patch at HDFS-11160 ensures BlockSender reads the correct version of
> metafile when there are concurrent writers.
> However, the implementation is not optimal, because it must always read the
> last partial chunk checksum from disk while holding FsDatasetImpl lock for
> every reader. It is possible to optimize this by keeping an up-to-date
> version of last partial checksum in-memory and reduce disk access.
> I am separating the optimization into a new jira, because maintaining the
> state of in-memory checksum requires a lot more work.
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