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https://issues.apache.org/jira/browse/HBASE-7878?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13616260#comment-13616260
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Eric Newton commented on HBASE-7878:
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Accumulo just writes out a LogEntry, which is a Writable. Read-back just opens
the file in HDFS and starts reading LogEntrys. It's slightly more complicated
than that because we just started to support encryption, so there's some
metadata at the beginning of the file.
Accumulo uses a simpler file format to avoid the check for an empty file that
occurs in SequenceFile. HBase uses SequenceFileLogReader to work around the
same issue.
But all this extra work might not be necessary now that we are properly closing
the file.
> recoverFileLease does not check return value of recoverLease
> ------------------------------------------------------------
>
> Key: HBASE-7878
> URL: https://issues.apache.org/jira/browse/HBASE-7878
> Project: HBase
> Issue Type: Bug
> Components: util
> Affects Versions: 0.95.0, 0.94.6
> Reporter: Eric Newton
> Assignee: Ted Yu
> Priority: Critical
> Fix For: 0.95.0, 0.98.0
>
> Attachments: 7878.94, 7878-94.addendum, 7878-94.addendum2,
> 7878-addendum.txt, 7878-trunk.addendum, 7878-trunk.addendum2,
> 7878-trunk-v10.txt, 7878-trunk-v11-test.txt, 7878-trunk-v12.txt,
> 7878-trunk-v13.txt, 7878-trunk-v14.txt, 7878-trunk-v15.patch,
> 7878-trunk-v16.txt, 7878-trunk-v2.txt, 7878-trunk-v3.txt, 7878-trunk-v4.txt,
> 7878-trunk-v5.txt, 7878-trunk-v6.txt, 7878-trunk-v7.txt, 7878-trunk-v8.txt,
> 7878-trunk-v9.txt, 7878-trunk-v9.txt
>
>
> I think this is a problem, so I'm opening a ticket so an HBase person takes a
> look.
> Apache Accumulo has moved its write-ahead log to HDFS. I modeled the lease
> recovery for Accumulo after HBase's lease recovery. During testing, we
> experienced data loss. I found it is necessary to wait until recoverLease
> returns true to know that the file has been truly closed. In FSHDFSUtils,
> the return result of recoverLease is not checked. In the unit tests created
> to check lease recovery in HBASE-2645, the return result of recoverLease is
> always checked.
> I think FSHDFSUtils should be modified to check the return result, and wait
> until it returns true.
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