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https://issues.apache.org/jira/browse/HDFS-6871?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Yi Liu updated HDFS-6871:
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Attachment: HDFS-6871.003.patch
The new patch extracts {{removeBlocks(…)}} outside the lock and after the
logSync. Since we modify the removing blocks logic of creating file with
overwrite, so I add a test to check the blocks of old file are cleaned after
create with overwrite.
> Improve NameNode performance when creating file
> -------------------------------------------------
>
> Key: HDFS-6871
> URL: https://issues.apache.org/jira/browse/HDFS-6871
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode, performance
> Reporter: Yi Liu
> Assignee: Yi Liu
> Priority: Critical
> Fix For: 2.6.0
>
> Attachments: HDFS-6871.001.patch, HDFS-6871.002.patch,
> HDFS-6871.003.patch
>
>
> Creating file with overwrite flag will cause NN fall into flush edit logs and
> block other requests if the file exists.
> When we create a file with overwrite flag (default is true) in HDFS, NN will
> remove original file if it exists. In FSNamesystem#startFileInternal, NN
> already holds the write lock, it calls {{deleteInt}} if the file exists,
> there is logSync in {{deleteInt}}. So in this case, logSync is under write
> lock, it will heavily affect the NN performance.
> We should ignore the force logSync in {{deleteInt}} in this case.
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