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From "Elliott Clark (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 Thu, 17 Dec 2015 08:10:47 GMT

    [ https://issues.apache.org/jira/browse/HBASE-14460?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15061691#comment-15061691
] 

Elliott Clark commented on HBASE-14460:
---------------------------------------

bq. A larger locked code block impacts the put operations too?
Not really. In the latest branches we've made the row locks reader/writer. That means that
there can be any number of puts for the same row going on. So holding the row lock until after
the mvcc has been fully applied shouldn't change the normal put flow. It also won't change
the increment flow.

The only place it will matter is when there are increments and puts going to the same row
from different clients. That's always going to be the case since we only have per row level
locks.

> [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.patch, client.test.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, hack.flamegraph-16593.svg,
hack.uncommitted.patch, 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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