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From "ramkrishna.s.vasudevan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-16890) Analyze the performance of AsyncWAL and fix the same
Date Thu, 27 Oct 2016 05:57:58 GMT

    [ https://issues.apache.org/jira/browse/HBASE-16890?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15610797#comment-15610797
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ramkrishna.s.vasudevan commented on HBASE-16890:
------------------------------------------------

Just posting as per Stack request to what was done.
bq.There is also a means of carrying unsync'd appends from one WAL to another if a WAL goes
unresponsive, a feature we'd like to keep (Another 'feature' of asyncwal that we don't have
in FSHLog is some size accounting so if N bytes of appends, sync regardless....we should keep
this too, something current FSHLog can't do because it intentionally lets appends and sync
run independent of each other).
Ok. Agree. 
bq. Any sense of how many syncs you were aggregating in your tests?
Am not sure how to account for this in particular. The JFR reports says most of the time is
spent in checksum as part of the sync call in case AsyncWAL but other than that I am not sure
specifically how to see that. But I got your intention out here. 
And one reason what I see there is a speed up in my case is that because of the hack I intentionally
come out of wait for some of the syncs than it was doing previously. But that should not be
major the factor for the gain here.

> 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, 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, 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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