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Date: Thu, 17 Dec 2015 20:50:47 +0000 (UTC)
From: "stack (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
Message-ID: <JIRA.12895334.1442898506000.58722.1450385447146@Atlassian.JIRA>
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 <JIRA.12895334.1442898506554@arcas>
Subject: [jira] [Commented] (HBASE-14460) [Perf Regression] Merge of MVCC
 and SequenceId (HBASE-HBASE-8763) slowed Increments, CheckAndPuts, batch
 operations
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    [ https://issues.apache.org/jira/browse/HBASE-14460?page=3Dcom.atlassia=
n.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=3D150=
62779#comment-15062779 ]=20

stack commented on HBASE-14460:
-------------------------------

bq. For branch-1.2, branch-1, and master we can just hold the lock longer i=
n doMiniBatchMutation and then there's no need for read-uncommitted.

I'd like to do general perf compare first before doing above. Will do in an=
other issue.

I believe I need the READ_UNCOMMITTED in this patch because mvcc is global =
to the region. At the end of the increment I add my write to mvcc but other=
 writes that have not yet completed may hold up my write being 'committed' =
in mvcc... meantime a new Increment could come in and not see the just-writ=
ten value in memstore.

Thanks Elliott.

> [Perf Regression] Merge of MVCC and SequenceId (HBASE-HBASE-8763) slowed =
Increments, CheckAndPuts, batch operations
> -------------------------------------------------------------------------=
------------------------------------------
>
>                 Key: HBASE-14460
>                 URL: https://issues.apache.org/jira/browse/HBASE-14460
>             Project: HBase
>          Issue Type: Bug
>          Components: Performance
>            Reporter: stack
>            Assignee: stack
>            Priority: Critical
>         Attachments: 0.94.test.patch, 0.98.test.patch, 1.0.80.flamegraph-=
7932.svg, 14460.txt, 98.80.flamegraph-11428.svg, HBASE-14460-discussion.pat=
ch, client.test.patch, flamegraph-13120.svg.master.singlecell.svg, flamegra=
ph-26636.094.100.svg, flamegraph-28066.098.singlecell.svg, flamegraph-28767=
.098.100.svg, flamegraph-31647.master.100.svg, flamegraph-9466.094.singlece=
ll.svg, hack.flamegraph-16593.svg, hack.uncommitted.patch, m.test.patch, re=
gion_lock.png, testincrement.094.patch, testincrement.098.patch, testincrem=
ent.master.patch
>
>
> As reported by =E9=88=B4=E6=9C=A8=E4=BF=8A=E8=A3=95 up on the mailing lis=
t -- see "Performance degradation between CDH5.3.1(HBase0.98.6) and CDH5.4.=
5(HBase1.0.0)" -- our unification of sequenceid and MVCC slows Increments (=
and other ops) as the mvcc needs to 'catch up' to our current point before =
we can read the last Increment value that we need to update.
> We can say that our Increment is just done wrong, we should just be writi=
ng Increments and summing on read, but checkAndPut as well as batching oper=
ations have the same issue. Fix.


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