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https://issues.apache.org/jira/browse/HBASE-17434?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15805533#comment-15805533
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Eshcar Hillel commented on HBASE-17434:
---------------------------------------
The current patch implements copy-on-write in the compaction pipeline level, it
does not use any CopyOnWrite data structures.
It does not add any synchronization.
It removes the synchronization from getSegments() which is invoked upon every
get and scan operation.
It uses LinkedList which implements addFirst() more efficiently than an array
field.
> New Synchronization Scheme for Compaction Pipeline
> --------------------------------------------------
>
> Key: HBASE-17434
> URL: https://issues.apache.org/jira/browse/HBASE-17434
> Project: HBase
> Issue Type: Bug
> Reporter: Eshcar Hillel
> Attachments: HBASE-17434-V01.patch
>
>
> A new copyOnWrite synchronization scheme is introduced for the compaction
> pipeline.
> The new scheme is better since it removes the lock from getSegments() which
> is invoked in every get and scan operation, and it reduces the number of
> LinkedList objects that are created at runtime, thus can reduce GC (not by
> much, but still...).
> In addition, it fixes the method getTailSize() in compaction pipeline. This
> method creates a MemstoreSize object which comprises the data size and the
> overhead size of the segment and needs to be atomic.
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