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From "Heng Chen (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-14460) [Perf Regression] Merge of MVCC and SequenceId (HBASE-HBASE-8763) slowed Increments, CheckAndPuts, batch operations
Date Mon, 14 Dec 2015 06:04:46 GMT

    [ https://issues.apache.org/jira/browse/HBASE-14460?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15055467#comment-15055467
] 

Heng Chen commented on HBASE-14460:
-----------------------------------

{quote}
If I run a test that has 100 threads each updating their own rows – i.e. no contention on
a row – then I see master branch completing before 0.94 does; i.e. master is faster. 
{quote}
are all the rows in one region?

> [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, 14460.txt, flamegraph-13120.svg.master.singlecell.svg,
flamegraph-26636.094.100.svg, flamegraph-28066.098.singlecell.svg, flamegraph-28767.098.100.svg,
flamegraph-31647.master.100.svg, flamegraph-9466.094.singlecell.svg, m.test.patch, region_lock.png,
testincrement.094.patch, testincrement.098.patch, testincrement.master.patch
>
>
> As reported by 鈴木俊裕 up on the mailing list -- 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 writing Increments
and summing on read, but checkAndPut as well as batching operations have the same issue. Fix.



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