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https://issues.apache.org/jira/browse/CASSANDRA-6689?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13944213#comment-13944213
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Pavel Yaskevich commented on CASSANDRA-6689:
--------------------------------------------
bq. 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.
I has thinking of thing as easy as replacing HeapAllocator.instance with
SlabAllocator.instance (which would only have a heap allocation enabled).
bq. 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.
If you have unslabbed_heap_buffers in your code then you better document it in
the config, because people would find it and create a issue for that. Rather
from that I don't care much about names as soon as they present what they do -
"{on}heap_slab" - means that those buffers are going to be allocated in the
on-heap slabs, same goes for "offheap_slab" (I was thinking of using
"direct_slab" but all of the code has it as "offheap"), "jvm_default" is just a
default way of allocating single buffers.
bq. heapAllocOnly is uglier and no better than allocateOnHeap. If you want,
make it allocateOnHeapOnly.
I'm fine with allocateOnHeapOnly if you like big names better, just
allocateOnHeap doesn't coalesce with a usage of the variable.
> 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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