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https://issues.apache.org/jira/browse/HDFS-15567?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Konstantin Shvachko updated HDFS-15567:
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Affects Version/s: 2.10.0
Assignee: Konstantin Shvachko
Status: Patch Available (was: Open)
Decided to go with option 1 exposing {{msync}} via {{FileSystem}} and
{{FileContext}}. See patch attached.
We can further implement {{msync}} for {{ViewFileSystem}}, which would try to
call it on all mount points, whichever supports it. {{WebHDFS}} is not built
for that as it doesn't have {{AlignmentContext}} and therefore cannot pass
state ids between NameNode and clients.
> [SBN Read] HDFS should expose msync() API to allow downstream applications
> call it explicetly.
> ----------------------------------------------------------------------------------------------
>
> Key: HDFS-15567
> URL: https://issues.apache.org/jira/browse/HDFS-15567
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: ha, hdfs-client
> Affects Versions: 2.10.0
> Reporter: Konstantin Shvachko
> Assignee: Konstantin Shvachko
> Priority: Major
> Attachments: HDFS-15567.001.patch
>
>
> Consistent reads from Standby introduced {{msync()}} API HDFS-13688, which
> updates client's state ID with current state of the Active NameNode to
> guarantee consistency of subsequent calls to an ObserverNode. Currently this
> API is exposed via {{DFSClient}} only, which makes it hard for applications
> to access {{msync()}}. One way is to use something like this:
> {code}
> if(fs instanceof DistributedFileSystem) {
> ((DistributedFileSystem)fs).getClient().msync();
> }
> {code}
> This should be exposed both for {{FileSystem}} and {{FileContext}}.
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