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https://issues.apache.org/jira/browse/HBASE-16890?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15656770#comment-15656770
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ramkrishna.s.vasudevan commented on HBASE-16890:
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I want to ask some dumb questions.
FSHLog calls WAL Sync - internally we write data to FSOutputStream and then we
will call a fsdos.sync or fsdos.hflush(). So what ever was written till that
point will be transffered from client to DNs and here we mark the packet as
'tosync = true'.
Now there is no DFSClient here - instead you try to directly right to DN. But I
could see that in any of the packets that you create you don't set 'sync =
true' but only when there is endBlock() you say lastPacket=true. So what
difference does this create?
> Analyze the performance of AsyncWAL and fix the same
> ----------------------------------------------------
>
> Key: HBASE-16890
> URL: https://issues.apache.org/jira/browse/HBASE-16890
> Project: HBase
> Issue Type: Sub-task
> Components: wal
> Affects Versions: 2.0.0
> Reporter: ramkrishna.s.vasudevan
> Assignee: ramkrishna.s.vasudevan
> Fix For: 2.0.0
>
> Attachments: AsyncWAL_disruptor.patch, AsyncWAL_disruptor_1
> (2).patch, AsyncWAL_disruptor_3.patch, AsyncWAL_disruptor_3.patch,
> AsyncWAL_disruptor_4.patch, AsyncWAL_disruptor_6.patch,
> HBASE-16890-rc-v2.patch, HBASE-16890-rc-v3.patch,
> HBASE-16890-remove-contention-v1.patch, HBASE-16890-remove-contention.patch,
> Screen Shot 2016-10-25 at 7.34.47 PM.png, Screen Shot 2016-10-25 at 7.39.07
> PM.png, Screen Shot 2016-10-25 at 7.39.48 PM.png, Screen Shot 2016-11-04 at
> 5.21.27 PM.png, Screen Shot 2016-11-04 at 5.30.18 PM.png, async.svg,
> classic.svg, contention.png, contention_defaultWAL.png
>
>
> Tests reveal that AsyncWAL under load in single node cluster performs slower
> than the Default WAL. This task is to analyze and see if we could fix it.
> See some discussions in the tail of JIRA HBASE-15536.
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