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https://issues.apache.org/jira/browse/HBASE-15046?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15073419#comment-15073419
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Elliott Clark edited comment on HBASE-15046 at 12/29/15 3:30 AM:
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bq.That was the whole point of rolling back the memstore, so that we can sync
the wal to the DNs without holding the row lock, I doubt we want to undo that
part.
There can be any number of updates in flight for a single row. So holding the
row lock longer doesn't have the down side that it used to. Since every row
lock is reader/writer the only time that holding the lock longer has any
performance issue is when there are puts and check/mutates in flight to the
same row. And @stack has already shown that increments are much faster by not
having to wait for mvcc ( made possible by holding the row lock longer).
was (Author: eclark):
bq.That was the whole point of rolling back the memstore, so that we can sync
the wal to the DNs without holding the row lock, I doubt we want to undo that
part.
There can be any number of updates in flight for a single row. So holding the
row lock longer doesn't have the down side that it used to.
> Perf test doing all mutation steps under row lock
> -------------------------------------------------
>
> Key: HBASE-15046
> URL: https://issues.apache.org/jira/browse/HBASE-15046
> Project: HBase
> Issue Type: Sub-task
> Components: Performance
> Reporter: stack
>
> This issue is about perf testing a redo of the write pipeline so that rather
> than:
> * take rowlock
> * start mvcc
> * append to WAL
> * add to memstore
> * sync WAL
> * let go of rowlock
> * finish up mvcc
> instead.... try...
> * take rowlock
> * start mvcc
> * append to WAL
> * sync WAL
> * add to memstore
> * finish up mvcc
> * let go of rowlock
> The latter is more straight-forward undoing need of rolling back memstore if
> all does not succeed.
> It might be slower though. This issue is a look-see/try it.
> The redo will also help address the parent issue in a more general way so we
> can do without the special-casing done for branch-1.0 and branch-1.1 done in
> a sibling subtask.
> Other benefits are that the current write pipeline is copy/pasted in a few
> places -- in append, increment and checkand* -- and a refactor will allow us
> to fix this duplication.
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