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https://issues.apache.org/jira/browse/HBASE-8877?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13700940#comment-13700940
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Dave Latham commented on HBASE-8877:
------------------------------------
A few changes in this patch compared to the latest similar patch on HBASE-8806:
- fixed the heap size logic to match the new fields
- wrapped a couple lines that were longer than 100 chars
- changed releaseMyRowLocks method to free the list of locks from the thread
local so that each thread doesn't wind up having very long empty lists hanging
around
- changed the row lock methods from public to package private as they are only
used inside HRegion (and by some tests)
- added some comments to checkAndMutate to make clear row it's reusing locks
- renamed new thread local field to rowLocksHeldByThread
> Reentrant row locks
> -------------------
>
> Key: HBASE-8877
> URL: https://issues.apache.org/jira/browse/HBASE-8877
> Project: HBase
> Issue Type: Bug
> Components: Coprocessors, regionserver
> Reporter: Dave Latham
> Assignee: Dave Latham
> Fix For: 0.95.2
>
> Attachments: HBASE-8877.patch
>
>
> HBASE-8806 revealed performance problems with batch mutations failing to
> reacquire the same row locks. It looks like HBASE-8806 will use a less
> intrusive change for 0.94 to have batch mutations track their own row locks
> and not attempt to reacquire them. Another approach will be to support
> reentrant row locks directly. This allows simplifying a great deal of
> calling code to no longer track and pass around lock ids.
> One affect this change will have is changing the RegionObserver coprocessor's
> methods preBatchMutate and postBatchMutate from taking a
> {{MiniBatchOperationInProgress<Pair<Mutation, Integer>> miniBatchOp}} to
> taking a {{MiniBatchOperationInProgress<Mutation> miniBatchOp}}. I don't
> believe CPs should be relying on these lock ids, but that's a potential
> incompatibility.
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