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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 07:33:46 GMT

    [ https://issues.apache.org/jira/browse/HBASE-14460?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15057499#comment-15057499

Jingcheng Du commented on HBASE-14460:

Most of the difference is what mvcc.await does in the beginning of the increment, checkAndMutate,
etc. operations, it only waits for the operations in its row. In the mvcc.await after the
operations, it is the same with the current way to wait for the finish of the current operation.
If it is a batch operation, all the row operation context in that batch will have the same
write number of a WriteEntry. This write number will be used in mvcc.await method in the beginning
of next increment operation.

> [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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