[jira] [Comment Edited] (HBASE-14460) [Perf Regression] Merge of MVCC and SequenceId (HBASE-HBASE-8763) slowed Increments, CheckAndPuts, batch operations

["stack (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-14460?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15057465#comment-15057465 ] 

stack edited comment on HBASE-14460 at 12/15/15 7:06 AM:
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[~jingcheng.du@intel.com] I'm not clear on how your patch works. Please explain it to those who are slower than you.

I see that at the start of the Increment, when we begin mvcc, we pass in this new RowContext. I see then that in begin, we run through contexts looking at write numbers to find the highest write number on a row which I suppose could be less than the one we are assigned by default; that'd be good.  How is row write number assigned?

Thanks.


was (Author: stack):
[~jingcheng.du@intel.com] I'm not clear on how your patch works. Please explain it to those who are slower than you.

I see that at the start of the Incrment, when we being mvcc, we pass in this new RowContext. I see then that in begin, we run through contexts looking at write numbers to find the highest write number on a row which I suppose could be less than the one we are assigned by default; that'd be good.  How is row write number assigned?

Thanks.

> [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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