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https://issues.apache.org/jira/browse/HDFS-13609?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16514540#comment-16514540
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Konstantin Shvachko commented on HDFS-13609:
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Looks like shadedclient failures are also in the trunk. I wouldn't worry about
it here.
# Looking at the patch I see that a lot of changes are related to adding new
parameter {{boolean optimizeLatency}} into
{{LogsPurgeable.selectInputStreams()}}, which in turn affected
{{JournalManager}} interface.
The parameter is actively used only in {{QuorumJournalManager}}. In all other
implementations it is ignored. In {{QuorumJournalManager.selectInputStreams()}}
implementation you require {{optimizeLatency}} to be the same as
{{inProgressOk}} except when {{optimizeLatency == false && nProgressOk ==
true}}. But in the latter case {{optimizeLatency}} is ignored. So my main
question is can we simply use {{inProgressOk}} as an indicator to optimize for
latency and drop the {{optimizeLatency}} parameter? This should simplify
changes a lot.
# In {{hdfs-default.xml}} rephrase "This will also enable tailing of edit logs
via" -> "This enables tailing of edit logs via". Like that you clarify it.
# Should {{dfs.ha.tail-edits.qjm.rpc.max-txns}} be a public or an undocumented
config parameter? I see there is a bunch of "Change with caution" properties in
{{hdfs-default.xml}}. This is exactly why we keep them undocumented.
> [Edit Tail Fast Path Pt 3] NameNode-side changes to support tailing edits via
> RPC
> ---------------------------------------------------------------------------------
>
> Key: HDFS-13609
> URL: https://issues.apache.org/jira/browse/HDFS-13609
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: ha, namenode
> Reporter: Erik Krogen
> Assignee: Erik Krogen
> Priority: Major
> Attachments: HDFS-13609-HDFS-12943.000.patch,
> HDFS-13609-HDFS-12943.001.patch, HDFS-13609-HDFS-12943.002.patch
>
>
> See HDFS-13150 for the full design.
> This JIRA is targetted at the NameNode-side changes to enable tailing
> in-progress edits via the RPC mechanism added in HDFS-13608. Most changes are
> in the QuorumJournalManager.
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