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https://issues.apache.org/jira/browse/HDDS-2382?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17123556#comment-17123556
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Attila Doroszlai commented on HDDS-2382:
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[~arp], yes, [both
layouts|https://github.com/apache/hadoop-ozone/blob/3ab76ce59d529aa4f468a72eb7aec187cb01a0bd/hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/common/impl/ChunkLayOutVersion.java#L124-L125]
perform the same [chunk dir
check|https://github.com/apache/hadoop-ozone/blob/3ab76ce59d529aa4f468a72eb7aec187cb01a0bd/hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/common/impl/ChunkLayOutVersion.java#L133-L150].
> Consider reducing number of file::exists() calls during write operation
> -----------------------------------------------------------------------
>
> Key: HDDS-2382
> URL: https://issues.apache.org/jira/browse/HDDS-2382
> Project: Hadoop Distributed Data Store
> Issue Type: Bug
> Components: Ozone Datanode
> Reporter: Rajesh Balamohan
> Assignee: Attila Doroszlai
> Priority: Major
> Labels: TriagePending, performance
>
> When writing 100-200 MB files with multiple threads, observed lots of
> {{[file::exists(])}} checks.
> For every 16 MB chunk, it ends up checking whether {{chunksLoc}} directory
> exists or not. (ref:
> [https://github.com/apache/hadoop-ozone/blob/master/hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/keyvalue/helpers/ChunkUtils.java#L239])
> Also, this check ({{ChunkUtils.getChunkFile}}) happens from 2 places.
> 1.org.apache.hadoop.ozone.container.common.transport.server.ratis.ContainerStateMachine.lambda$handleWriteChunk
> 2.org.apache.hadoop.ozone.container.common.transport.server.ratis.ContainerStateMachine.lambda$applyTransaction
> Note that these are folders and not actual chunk filenames. It would be
> helpful to reduce this check, if we track create/delete of these folders.
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