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https://issues.apache.org/jira/browse/HDFS-1172?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14940761#comment-14940761
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Masatake Iwasaki commented on HDFS-1172:
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bq. We'd better place the new "adding block to pending replica queue" logic
only in checkReplication.
Thanks for the comment again. We can not get expected nodes in
{{BlockManager#checkReplication}} because BlockUnderConstructionFeature is
already removed by {{BlockInfo#convertToCompleteBlock}} at that point. I'm
trying to update the pendingReplications only in the code path of
{{completeFile}} now.
> Blocks in newly completed files are considered under-replicated too quickly
> ---------------------------------------------------------------------------
>
> Key: HDFS-1172
> URL: https://issues.apache.org/jira/browse/HDFS-1172
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namenode
> Affects Versions: 0.21.0
> Reporter: Todd Lipcon
> Assignee: Masatake Iwasaki
> Attachments: HDFS-1172-150907.patch, HDFS-1172.008.patch,
> HDFS-1172.009.patch, HDFS-1172.010.patch, HDFS-1172.patch, hdfs-1172.txt,
> hdfs-1172.txt, replicateBlocksFUC.patch, replicateBlocksFUC1.patch,
> replicateBlocksFUC1.patch
>
>
> I've seen this for a long time, and imagine it's a known issue, but couldn't
> find an existing JIRA. It often happens that we see the NN schedule
> replication on the last block of files very quickly after they're completed,
> before the other DNs in the pipeline have a chance to report the new block.
> This results in a lot of extra replication work on the cluster, as we
> replicate the block and then end up with multiple excess replicas which are
> very quickly deleted.
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