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https://issues.apache.org/jira/browse/HBASE-11126?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13999697#comment-13999697
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Anoop Sam John commented on HBASE-11126:
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preGetClosestRowBefore
preGetOp
preExist
prePut
preDelete
preCheckAndPut
preCheckAndDelete
preAppend
preIncrement
These are pre hooks on row based ops.
In case of Put/Delete we have preBatchMutatate() hook which will be called
after obtaining rowlock. Also the read ops dont have row locking.
So we will need hooks after row locking in
preCheckAndPut
preCheckAndDelete
preAppend
preIncrement
bq.How about we attempt to move all existing RegionObserver pre* hooks to
execute under row lock?
That wont be a correct way IMHO. We know that any costly operation doing in
such a pre hook will not be desirable. So I think we should not change the CP
behaviour. Atleast in 98. So the option would be to come up with new hooks.
> Add RegionObserver pre hooks that operate under row lock
> --------------------------------------------------------
>
> Key: HBASE-11126
> URL: https://issues.apache.org/jira/browse/HBASE-11126
> Project: HBase
> Issue Type: Improvement
> Affects Versions: 0.99.0, 0.98.3
> Reporter: Andrew Purtell
> Assignee: ramkrishna.s.vasudevan
>
> The coprocessor hooks were placed outside of row locks. This was meant to
> sidestep performance issues arising from significant work done within hook
> invocations. However as the security code increases in sophistication we are
> now running into concurrency issues trying to use them as a result of that
> early decision. Since the initial introduction of coprocessor upcalls there
> has been some significant refactoring done around them and concurrency
> control in core has become more complex. This is potentially an issue for
> many coprocessor users.
> We should do either:\\
> - Move all existing RegionObserver pre* hooks to execute under row lock.
> - Introduce a new set of RegionObserver pre* hooks that execute under row
> lock, named to indicate such.
> The second option is less likely to lead to surprises.
> All RegionObserver hook Javadoc should be updated with advice to the
> coprocessor implementor not to take their own row locks in the hook. If the
> current thread happens to already have a row lock and they try to take a lock
> on another row, there is a deadlock risk.
> As always a drawback of adding hooks is the potential for performance impact.
> We should benchmark the impact and decide if the second option above is a
> viable choice or if the first option is required.
> Finally, we should introduce a higher level interface for managing the
> registration of 'user' code for execution from the low level hooks. I filed
> HBASE-11125 to discuss this further.
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