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https://issues.apache.org/jira/browse/HDFS-2018?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13083542#comment-13083542
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Todd Lipcon commented on HDFS-2018:
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right, but when loading a sequence of logs, it will call selectStream() for
each starting txid in the sequence. Then, the selectStream() call causes each
journal to have to look at its contents. Then, FileJournalManager has a lot of
caching in it to try to make this more efficient, from what I can tell. I'm
about halfway through the alternate approach - I think it will end up being
fewer lines of code and a bit simpler.
> 1073: Move all journal stream management code into one place
> ------------------------------------------------------------
>
> Key: HDFS-2018
> URL: https://issues.apache.org/jira/browse/HDFS-2018
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Ivan Kelly
> Assignee: Ivan Kelly
> Fix For: 0.23.0
>
> Attachments: HDFS-2018.diff, HDFS-2018.diff, HDFS-2018.diff,
> HDFS-2018.diff, HDFS-2018.diff, HDFS-2018.diff, HDFS-2018.diff,
> HDFS-2018.diff, HDFS-2018.diff, HDFS-2018.diff, HDFS-2018.diff,
> HDFS-2018.diff, HDFS-2018.diff, HDFS-2018.diff, HDFS-2018.diff, HDFS-2018.diff
>
>
> Currently in the HDFS-1073 branch, the code for creating output streams is in
> FileJournalManager and the code for input streams is in the inspectors. This
> change does a number of things.
> - Input and Output streams are now created by the JournalManager.
> - FSImageStorageInspectors now deals with URIs when referring to edit logs
> - Recovery of inprogress logs is performed by counting the number of
> transactions instead of looking at the length of the file.
> The patch for this applies on top of the HDFS-1073 branch + HDFS-2003 patch.
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