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https://issues.apache.org/jira/browse/HDFS-1580?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13041627#comment-13041627
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Ivan Kelly commented on HDFS-1580:
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Finalizing in getNumTransactions is a bit messy, because its difficult to tell
if a inprogress file is actually inprogress or the result of a crashed
namenode. I tried it in HDFS-2018, but ended up creating an explicit
recoverUnclosedStreams() call, which only gets called on loading
(getNumTransactions is called in other places, such as checkpointing). It would
be possible to hide this inside the JournalManager, but then we'd have to make
some sort of locking mechanism to ensure an inprogress stream doesn't get
finalised while it is writing. This is simple for bookkeeper, but for
filesystems we'd need some sort of lease mechanism.
> Add interface for generic Write Ahead Logging mechanisms
> --------------------------------------------------------
>
> Key: HDFS-1580
> URL: https://issues.apache.org/jira/browse/HDFS-1580
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Ivan Kelly
> Fix For: Edit log branch (HDFS-1073)
>
> Attachments: EditlogInterface.1.pdf, EditlogInterface.2.pdf,
> HDFS-1580+1521.diff, HDFS-1580.diff, HDFS-1580.diff, HDFS-1580.diff,
> generic_wal_iface.pdf, generic_wal_iface.pdf, generic_wal_iface.pdf,
> generic_wal_iface.txt
>
>
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