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From: "Dave Latham (JIRA)" <jira@apache.org>
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Subject: [jira] [Created] (HBASE-8877) Reentrant row locks
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Dave Latham created HBASE-8877:
----------------------------------

             Summary: 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


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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