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https://issues.apache.org/jira/browse/HADOOP-16185?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Steve Loughran resolved HADOOP-16185.
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Resolution: Won't Fix
> S3Guard: Optimize performance of handling OOB operations in non-authoritative
> mode
> ----------------------------------------------------------------------------------
>
> Key: HADOOP-16185
> URL: https://issues.apache.org/jira/browse/HADOOP-16185
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: fs/s3
> Affects Versions: 3.3.0
> Reporter: Gabor Bota
> Priority: Minor
>
> HADOOP-15999 modifies the S3Guard's non-authoritative mode, so when S3Guard
> runs non-authoritative, every {{fs.getFileStatus}} will check S3 because we
> don't handle the MetadataStore as a single source of truth. This has a
> negative performance impact.
>
> In other words HADOOP-15999 is going to reinstate the HEAD on every read, so
> making non-auth S3Guard a bit slower. We could think about addressing that by
> moving the checks into the input stream itself. That is: the first GET which
> returns data will also act as the metadata check. That'd mean the read
> context will need updating with some "metastoreProcessHeader" callback to
> invoke on the first GET.
> The good news is that because it's reading a file, its only one HTTP HEAD
> request: no need to do any of the other two directory probes except in the
> case that the file isn't there.
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