[jira] [Commented] (HBASE-2645) HLog writer can do 1-2 sync operations after lease has been recovered for split process.

["vamshi (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-2645?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13070384#comment-13070384 ] 

vamshi commented on HBASE-2645:
-------------------------------

Hi Todd,may be in this place this question is irrelevant. But please let me know whether we can implement a distributed hashing in HBase for fast lookup/ scanning purpose?? i want to implement scalable data structure i.e DHT in Hbase, for that how can i proceed? Thank you.

> HLog writer can do 1-2 sync operations after lease has been recovered for split process.
> ----------------------------------------------------------------------------------------
>
>                 Key: HBASE-2645
>                 URL: https://issues.apache.org/jira/browse/HBASE-2645
>             Project: HBase
>          Issue Type: Bug
>          Components: filters
>    Affects Versions: 0.90.4
>            Reporter: Cosmin Lehene
>            Assignee: Todd Lipcon
>            Priority: Blocker
>             Fix For: 0.94.0
>
>
> TestHLogSplit.testLogCannotBeWrittenOnceParsed is failing. 
> This test starts a thread that writes one edit to the log, syncs and counts. During this, a HLog.splitLog operation is started. splitLog recovers the log lease before reading the log, so that the original regionserver could not wake up and write after the split process started.  
> The test compares the number of edits reported by the split process and by the writer thread. Writer thread (called zombie in the test) should report <=  than the splitLog (sync() might raise after the last edit gets written and the edit won't get counted by zombie thread). However it appears that the zombie counts 1-2 more edits. So it looks like it can sync without a lease.
> This might be a hdfs-0.20 related issue. 

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