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https://issues.apache.org/jira/browse/CASSANDRA-2252?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Stu Hood updated CASSANDRA-2252:
--------------------------------
Attachment: 2252-v1.tgz
We've been developing a very similar patch in parallel: attached as
2252-alternate-v1.tgz.
The key differences seem to be:
* Original removes interning from deserialization, alternate encapsulates it
* Alternate has support for allocating reconciled counter columns (the result
of merging counters) in slabs
* Original uses JNA for direct memory access, alternate uses
ByteBuffer.allocateDirect
* Alternate uses the allocation count of the Memtable's allocator to measure
throughput for thresholds (less accurate, but necessary to track the true
memory usage of counters)
We've tested the alternate patch in a production setting with counter mutations
to multiple column families: it reduced our fragmentation enough to double the
time between promotion failures, but it does not fully eliminate fragmentation.
> off-heap memtables
> ------------------
>
> Key: CASSANDRA-2252
> URL: https://issues.apache.org/jira/browse/CASSANDRA-2252
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Jonathan Ellis
> Assignee: Jonathan Ellis
> Fix For: 0.8
>
> Attachments: 0001-add-MemtableAllocator.txt,
> 0002-add-off-heap-MemtableAllocator-support.txt, 2252-alternate-v1.tgz
>
>
> The memtable design practically actively fights Java's GC design. Todd
> Lipcon gave a good explanation over on HBASE-3455.
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