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https://issues.apache.org/jira/browse/HDFS-16043?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17355104#comment-17355104
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Xiaoqiao He commented on HDFS-16043:
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Thanks [~zhuxiangyi] for your works. It is interesting improvement. Just have a
quick glance, it seems that collect all blocks pending delete and postpone to
operate asynchronously, right?
I am not sure if it is works fine on HA mode or is it works same on both ANN
and SBN?
BTW there are different check failures at PR, not sure if it is related with
this changes.
Thanks again.
> HDFS : Delete performance optimization
> --------------------------------------
>
> Key: HDFS-16043
> URL: https://issues.apache.org/jira/browse/HDFS-16043
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs, namanode
> Affects Versions: 3.4.0
> Reporter: Xiangyi Zhu
> Assignee: Xiangyi Zhu
> Priority: Major
> Labels: pull-request-available
> Attachments: 20210527-after.svg, 20210527-before.svg
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> The deletion of the large directory caused NN to hold the lock for too long,
> which caused our NameNode to be killed by ZKFC.
> Through the flame graph, it is found that its main time-consuming
> calculation is QuotaCount when removingBlocks(toRemovedBlocks) and deleting
> inodes, and removeBlocks(toRemovedBlocks) takes a higher proportion of time.
> h3. solution:
> 1. RemoveBlocks is processed asynchronously. A thread is started in the
> BlockManager to process the deleted blocks and control the lock time.
> 2. QuotaCount calculation optimization, this is similar to the optimization
> of this Issue HDFS-16000.
> h3. Comparison before and after optimization:
> Delete 1000w Inode and 1000w block test.
> *before:*
> remove inode elapsed time: 7691 ms
> remove block elapsed time :11107 ms
> *after:*
> remove inode elapsed time: 4149 ms
> remove block elapsed time :0 ms
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