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From "Jingcheng Du (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 Tue, 15 Dec 2015 09:45:46 GMT

    [ https://issues.apache.org/jira/browse/HBASE-14460?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15057719#comment-15057719
] 

Jingcheng Du commented on HBASE-14460:
--------------------------------------

in the method begin(RowOperationContext... rowOperationContexts), it does several things.
1. Generate the next write number.
2. Get the last write number that the current WritenEntry concerns ( by comparing the exiting
RowOperationContext in this batch and get the biggest one).
3. Set the next writer number for each RowOperationContext in this batch.
4. Set the next writer number to the current WriteEntry and add it to the write queue.

> [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, HBASE-14460-discussion.patch,
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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