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https://issues.apache.org/jira/browse/CASSANDRA-6689?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13944136#comment-13944136
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Benedict commented on CASSANDRA-6689:
-------------------------------------
bq. One more thing I forgot to mention which is for consideration, we might
take advantage of SlabAllocator (on-heap) to accommodate all of the temporary
buffers created by copying from Memtable so when that allocation spills to
oldgen it would create less fragmentation in there.
This is likely to require as much complexity as RefAction to ensure resource
cleanup, at which point we might as well just have proper zero copy.
As to your suggested changes, I am fine with most of the generics changes, but
-1 on several of your renames and your config note changes:
unslabbed_heap_buffers is *not* intended to be included in the config file, as
it is very much discouraged. Including "slab" in the name adds nothing, whereas
buffers permits other non-buffer implementations in future without confusion in
naming/renaming. I might change offheap_buffers to direct_buffers for
consistency with the JDK though.
heapAllocOnly is uglier and no better than allocateOnHeap. If you want, make it
allocateOnHeapOnly.
> Partially Off Heap Memtables
> ----------------------------
>
> Key: CASSANDRA-6689
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6689
> Project: Cassandra
> Issue Type: New Feature
> Components: Core
> Reporter: Benedict
> Assignee: Benedict
> Labels: performance
> Fix For: 2.1 beta2
>
> Attachments: CASSANDRA-6689-final-changes.patch,
> CASSANDRA-6689-small-changes.patch
>
>
> Move the contents of ByteBuffers off-heap for records written to a memtable.
> (See comments for details)
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