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https://issues.apache.org/jira/browse/HBASE-12751?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14638576#comment-14638576
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stack commented on HBASE-12751:
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bq. People were really digging into sequence id a lot on tests.
Crew on your side [~eclark]? Some notes:
https://docs.google.com/document/d/16beczDie-KU1uSpJvd0GoUlQbPtQBL93rOOPqnE5Ma0/edit#
bq. Do we want to make the locking fair?
I think so as a means of evening out the latencies.
bq. All edits are queued in the wal before they are put in the memstore... Our
comparitor on the map does that.
Let me look at the patch again. The above description sounds like how it mostly
worked previous. Let me see.... Thanks E.
> Allow RowLock to be reader writer
> ---------------------------------
>
> Key: HBASE-12751
> URL: https://issues.apache.org/jira/browse/HBASE-12751
> Project: HBase
> Issue Type: Bug
> Components: regionserver
> Affects Versions: 2.0.0, 1.3.0
> Reporter: Elliott Clark
> Assignee: Elliott Clark
> Fix For: 2.0.0, 1.3.0
>
> Attachments: HBASE-12751-v1.patch, HBASE-12751-v10.patch,
> HBASE-12751-v10.patch, HBASE-12751-v11.patch, HBASE-12751-v12.patch,
> HBASE-12751-v13.patch, HBASE-12751-v14.patch, HBASE-12751-v15.patch,
> HBASE-12751-v16.patch, HBASE-12751-v2.patch, HBASE-12751-v3.patch,
> HBASE-12751-v4.patch, HBASE-12751-v5.patch, HBASE-12751-v6.patch,
> HBASE-12751-v7.patch, HBASE-12751-v8.patch, HBASE-12751-v9.patch,
> HBASE-12751.patch
>
>
> Right now every write operation grabs a row lock. This is to prevent values
> from changing during a read modify write operation (increment or check and
> put). However it limits parallelism in several different scenarios.
> If there are several puts to the same row but different columns or stores
> then this is very limiting.
> If there are puts to the same column then mvcc number should ensure a
> consistent ordering. So locking is not needed.
> However locking for check and put or increment is still needed.
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