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https://issues.apache.org/jira/browse/HDFS-17218?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17774492#comment-17774492
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Haiyang Hu commented on HDFS-17218:
-----------------------------------
Thanks [~zhangshuyan] for you comment.
{quote}
I think the root cause here is that NameNode has no timeout mechanism for
handling excess replicas, just like PendingReconstructionMonitor in processing
block reconstruction.
{quote}
It is also a solution for NameNode to add the logic of a timeout mechanism to
handle redundant replicas.
but not sure if this will increase the pressure on NN?
we can discuss further it.
> NameNode should remove its excess blocks from the ExcessRedundancyMap When a
> DN registers
> -----------------------------------------------------------------------------------------
>
> Key: HDFS-17218
> URL: https://issues.apache.org/jira/browse/HDFS-17218
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namanode
> Reporter: Haiyang Hu
> Assignee: Haiyang Hu
> Priority: Major
> Labels: pull-request-available
> Attachments: image-2023-10-12-15-52-52-336.png
>
>
> Currently found that DN will lose all pending DNA_INVALIDATE blocks if it
> restarts.
> *Root case*
> Current DN enables asynchronously deletion, it have many pending deletion
> blocks in memory.
> when DN restarts, these cached blocks may be lost. it causes some blocks in
> the excess map in the namenode to be leaked and this will result in many
> blocks having more replicas then expected.
> *solution*
> Consider NameNode should remove its excess blocks from the
> ExcessRedundancyMap When a DN registers,
> this approach will ensure that when processing the DN's full block report,
> the 'processExtraRedundancy' can be performed according to the actual of the
> blocks.
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