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https://issues.apache.org/jira/browse/CASSANDRA-1469?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12906351#action_12906351
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Matthew F. Dennis commented on CASSANDRA-1469:
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A hybrid solution is to have the small, medium, large configs and the start
script just chooses and symlinks one on startup. This provides somewhat
consistent sizing from user to user as well as letting us pick memtable
defaults that work with the config in question.
> adaptive default heap size
> --------------------------
>
> Key: CASSANDRA-1469
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1469
> Project: Cassandra
> Issue Type: New Feature
> Components: Packaging
> Reporter: Jonathan Ellis
> Fix For: 0.7 beta 2
>
>
> Cassandra comes out of the box with very conservative defaults, especially in
> -Xmx and memtable sizes, which leads to complaints of poor performance or
> even OOM conditions under heavy load. But changing these to be aggressive
> can cause the same problem: most servers enable swap out of the box, so
> asking for a 4GB or 8GB heap could allocate happily but also cause problems
> when it starts paging.
> Proposed solution is to update the start script to set Xmx to half of system
> ram ("free -m | awk '/Mem:/ {print $2}'"). Memtable defaults will have to be
> handled by Java, but we can do that based on heap size (Runtime.maxMemory).
> An alternative suggestion was to provide "small", "medium", "large"
> configurations, but this plays poorly with rpm and deb packages. I think the
> adaptive approach is more promising.
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