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https://issues.apache.org/jira/browse/HBASE-8877?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13708016#comment-13708016
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Lars Hofhansl commented on HBASE-8877:
--------------------------------------
0.94 patch looks good. I played through scenarios where the client provides a
lock id, it should work find in all cases (as long as obtainRowLock does not
acquire reentrant locks, which is the case).
This worries me a little bit:
{code}
- LOG.warn("Release unknown lockId: " + lockId);
+ // Row not locked. Likely released by the same thread already.
return;
{code}
We're loosing a double check here. Not a deal breaker, though.
Also, while we're at it, let's fix the typo here:
{code}
+ if (rowLockContext == null) {
LOG.error("Releases row not locked, lockId: " + lockId + " row: "
+ rowKey);
{code}
"Releases" -> "Released". :)
> 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-8877-0.94-microbenchmark.txt,
> HBASE-8877-0.94.patch, HBASE-8877.patch, HBASE-8877-v2.patch,
> HBASE-8877-v3.patch, hbase-8877-v4-microbenchmark.txt, HBASE-8877-v4.patch,
> HBASE-8877-v5.patch, HBASE-8877-v6.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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