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https://issues.apache.org/jira/browse/HDFS-2018?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13091414#comment-13091414
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Jitendra Nath Pandey commented on HDFS-2018:
--------------------------------------------
> 3. Todd raised some concerns about removing the caching introduced in
> HDFS-2018, Sanjay and Jitendra are going to
> take a look and comment.
I discussed with Sanjay and Suresh regarding the caching of edit log file
names in FileJournalManager. We agreed that the cache is not really needed in
the FileJournalManager, because there is not any significant performance
concern. The cache for list of valid editlog files in FileJournalManager is
used only for recovery for a read. I think this cache can be removed once
explicit recoverLogs API is introduced. This should address Todd's concern.
So the following should let us reach an agreeable patch:
1. Modify Ivan's patch to introduce recoverLogs API.
2. The point (1) above will let us remove the cache from FileJournalManager.
3. As agreed before getEditLogManifest should be moved to
JournalAdminInterface, but we can leave it for later as mentioned in Eli's
comment, so no changes for this in HDFS-2018.
> 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, hdfs-2018-otherapi.txt, hdfs-2018.txt
>
>
> 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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