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https://issues.apache.org/jira/browse/HDFS-13610?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16540964#comment-16540964
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Konstantin Shvachko commented on HDFS-13610:
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For [~csun]'s comments:
(1) {{lowestTxnId}} is initialized to {{-1}}, so it seems we need to check if
it is negative.
(2) Layout versions are always a negative numbers. So using {{0}} instead of
{{Integer.MAX_VALUE}} as initial value is appropriate and preferrable.
(3) Actually the entire log message in {{updateLayoutVersion()}} is confusing.
It should state the oldLV, newLV, and newStartTxn. The LVs can jump, so it's
better to know both.
> [Edit Tail Fast Path Pt 4] Cleanup: integration test, documentation, remove
> unnecessary dummy sync
> --------------------------------------------------------------------------------------------------
>
> Key: HDFS-13610
> URL: https://issues.apache.org/jira/browse/HDFS-13610
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: ha, journal-node, namenode
> Reporter: Erik Krogen
> Assignee: Erik Krogen
> Priority: Major
> Attachments: HDFS-13610-HDFS-12943.000.patch,
> HDFS-13610-HDFS-12943.001.patch, HDFS-13610-HDFS-12943.002.patch,
> HDFS-13610-HDFS-12943.003.patch
>
>
> See HDFS-13150 for full design.
> This JIRA is targeted at cleanup tasks:
> * Add in integration testing. We can expand {{TestStandbyInProgressTail}}
> * Documentation in HDFSHighAvailabilityWithQJM
> * Remove the dummy sync added as part of HDFS-10519; it is unnecessary since
> now in-progress tailing does not rely on the JN committedTxnId
> A few bugs are also fixed:
> * Due to changes in HDFS-13609 to enable use of the RPC mechanism whenever
> inProgressOK is true, there were codepaths which would use the RPC mechanism
> even when dfs.ha.tail-edits.in-progress was false, meaning that the JNs did
> not enable the cache. Update the QJM logic to only use selectRpcInputStreams
> if this config is true.
> * Fix a false error logged when the layout version changes
> * Fix the logging when a layout version change occurs to avoid printing out a
> placeholder value (Integer.MAX_VALUE)
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