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https://issues.apache.org/jira/browse/CASSANDRA-8150?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14219967#comment-14219967
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Jeremiah Jordan commented on CASSANDRA-8150:
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While I agree all of that sounds nice for read heavy workloads. Have you used
these settings with a write heavy workload?
>From my experience when you have a write heavy workload, your young gen fills
>up with memtable data, which will and should be promoted to old gen. So if
>you set your young gen size high, it takes for ever to copy all that stuff to
>old gen. If you increase the MaxTenuringThreshold it makes that even worse,
>as all of the memtable data has to get copied back and forth inside young gen
>X times, and then there is even more memtable stuff which will build up, so
>the copy to old gen takes that much longer.
> Simplify and enlarge new heap calculation
> -----------------------------------------
>
> Key: CASSANDRA-8150
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8150
> Project: Cassandra
> Issue Type: Improvement
> Components: Config
> Reporter: Matt Stump
> Assignee: Brandon Williams
>
> It's been found that the old twitter recommendations of 100m per core up to
> 800m is harmful and should no longer be used.
> Instead the formula used should be 1/3 or 1/4 max heap with a max of 2G. 1/3
> or 1/4 is debatable and I'm open to suggestions. If I were to hazard a guess
> 1/3 is probably better for releases greater than 2.1.
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