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https://issues.apache.org/jira/browse/CASSANDRA-6544?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13864746#comment-13864746
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Vijay edited comment on CASSANDRA-6544 at 1/7/14 10:05 PM:
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Hi Jonathan, Yep in addition... if we can create a a offheap slab allocator
(and reuse the slabs) it will help in reducing the memory fragmentation. Hope
that make sense.
was (Author: vijay2...@yahoo.com):
Hi Jonathan, Yep in addition... if we can create a a offheap slab allocator
(and reuse the slabs) it will help in reducing the memory fragmentation. Hope
that make sure.
> Reduce GC activity during compaction
> ------------------------------------
>
> Key: CASSANDRA-6544
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6544
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Vijay
> Assignee: Vijay
> Fix For: 2.1
>
>
> We are noticing increase in P99 while the compactions are running at full
> stream. Most of it is because of the increased GC activity (followed by full
> GC).
> The obvious solution/work around is to throttle the compactions, but with
> SSD's we can get more disk bandwidth for reads and compactions.
> It will be nice to move the compaction object allocations off heap. First
> thing to do might be create a Offheap Slab allocator with the size as the
> compaction in memory size and recycle it.
> Also we might want to make it configurable so folks can disable it when they
> don't have off-heap memory to reserve.
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