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https://issues.apache.org/jira/browse/HBASE-17924?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16394871#comment-16394871
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mimani commented on HBASE-17924:
--------------------------------
Forgive my ignorance, Can you point me on how to apply this patch on
hbase-1.4.2 ?
> Consider sorting the row order when processing multi() ops before taking
> rowlocks
> ---------------------------------------------------------------------------------
>
> Key: HBASE-17924
> URL: https://issues.apache.org/jira/browse/HBASE-17924
> Project: HBase
> Issue Type: Improvement
> Affects Versions: 2.0.0, 1.1.8
> Reporter: Andrew Purtell
> Assignee: Allan Yang
> Priority: Major
> Fix For: 2.0.0, 1.4.0
>
> Attachments: HBASE-17924.patch, HBASE-17924.v0.patch,
> HBASE-17924.v2.patch, HBASE-17924.v3.patch, HBASE-17924.v4.patch,
> HBASE-17924.v5.patch
>
>
> When processing a batch mutation, we take row locks in whatever order the
> mutations were added to the multi op by the client.
>
> {noformat}
> RSRpcServices#multi -> RSRpcServices#mutateRows -> HRegion#mutateRow ->
> HRegion#mutateRowsWithLocks -> HRegion#processRowsWithLocks
> {noformat}
> Or
> {noformat}
> RSRpcServices#multi -> RSRpcServices#doNonAtomicRegionMutation ->
> HRegion#get
> | HRegion#append
> | HRegion#increment
> | HRegionServer#doBatchOp -> HRegion#batchMutate ->
> HRegion#doMiniBatchMutation
> {noformat}
>
> multi() is fed by client APIs that accept a RowMutations object containing
> actions for multiple rows. The container for ops inside RowMutations is an
> ArrayList, which doesn't change the ordering of objects added to it. The
> protobuf implementation of the messages for multi ops do not reorder the list
> of actions. When processing multi ops we iterate over the actions in the
> order rehydrated from protobuf.
> We should discuss sorting the order of ops by row key when processing multi()
> ops before taking row locks. Does this make lock ordering more predictable
> for server side operations? Yes, but potentially surprising for the client,
> right? Is there any legitimate reason we should take locks out of row key
> sorted order because the client has structured the request as such?
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