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https://issues.apache.org/jira/browse/CASSANDRA-6689?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13946318#comment-13946318
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Benedict edited comment on CASSANDRA-6689 at 3/25/14 1:14 PM:
--------------------------------------------------------------
-Agreed-. Pushed updated version to branch, which also modifies the
FileUtils.clean() code to be the neater direct cast, and to check for the
possibility by actually attempting a clean of a DirectByteBuffer.
bq. and just fail over to the heap allocation
I've opted for dying with an error message, and prompting the user to change
the config, but while this is less in keeping with what is the normal approach,
I think the danger of eating up all your memory (and possibly crashing with OOM
at random times) is bad enough to warrant the break from the norm, and simply
falling back to heap allocation doesn't allow you to fulfil the config spec, as
we cannot simply add the offheap space to the onheap space, as this would
inflate the ratio of heap space used, and ignoring the offheap space might be
particularly bad in e.g. later non-buffered implementations, as the heap space
could have been tuned down in the knowledge it is less necessary.
I think it's better to say: cannot fulfil your request, please advise.
was (Author: benedict):
-Agreed-. Pushed updated version to branch, which also modifies the
FileUtils.clean() code to be the neater direct cast, and to check for the
possibility by actually attempting a clean of a DirectByteBuffer.
bq. and just fail over to the heap allocation
I've opted for dying with an error message, and prompting the user to change
the config, but while this is less in keeping with what is the normal approach,
I think the danger of eating up all your memory (and possibly crashing with OOM
at random times) is bad enough to warrant the break from the norm.
> 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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