[jira] [Created] (HDDS-2382) Consider reducing number of file::exists() calls during write operation

["Rajesh Balamohan (Jira)" <ji...@apache.org>]

Rajesh Balamohan created HDDS-2382:
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             Summary: 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


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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