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https://issues.apache.org/jira/browse/HDFS-1765?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13164509#comment-13164509
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Uma Maheswara Rao G commented on HDFS-1765:
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I should have put the namesystem unlock in finally even though
chooseUnderReplicatedBlocks doesn't throw exception for more safe.
{code}
neededReplications.chooseUnderReplicatedBlocks(blocksToProcess);
+ namesystem.writeUnlock();
{code}
I will include this point in next patch along with the review comments if any.
Thanks
Uma
> Block Replication should respect under-replication block priority
> -----------------------------------------------------------------
>
> Key: HDFS-1765
> URL: https://issues.apache.org/jira/browse/HDFS-1765
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: name-node
> Affects Versions: 0.23.0
> Reporter: Hairong Kuang
> Assignee: Hairong Kuang
> Fix For: 0.24.0
>
> Attachments: HDFS-1765.patch, HDFS-1765.patch, HDFS-1765.pdf,
> underReplicatedQueue.pdf
>
>
> Currently under-replicated blocks are assigned different priorities depending
> on how many replicas a block has. However the replication monitor works on
> blocks in a round-robin fashion. So the newly added high priority blocks
> won't get replicated until all low-priority blocks are done. One example is
> that on decommissioning datanode WebUI we often observe that "blocks with
> only decommissioning replicas" do not get scheduled to replicate before other
> blocks, so risking data availability if the node is shutdown for repair
> before decommission completes.
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