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https://issues.apache.org/jira/browse/CASSANDRA-10403?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14938282#comment-14938282
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Joshua McKenzie commented on CASSANDRA-10403:
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bq. I'd prefer not to make too many assumptions about confirmation or (human)
memory bias on this. We will not get off this carousel without actual data.
Fair point, and I agree on the fact that all this needs further exploration.
Unfortunately we have neither infinite time nor resources to get ready for 3.0,
so there's a reduction in scope as to what this ticket's trying to solve.
bq. if we simply align the GC settings to the type of hardware that they work
well for.
Shouldn't the read/write workload distribution also play into that?
So after being a PITA and devil's advocate on this ticket, the end perspective
I come down to is: there's a bunch of different workloads and a bunch of
different hardware that C* runs on, and the idea of having a default that's
optimal for everyone is unrealistic. It may very well be that G1 is a better
"good enough" default for most distributions, large heap or no, and that's the
conversation on IRC that led Jonathan to his comment on the other ticket to go
with it.
[JEP 248|http://openjdk.java.net/jeps/248] seems to imply that Oracle thinks
that's the case.
Within the scope of this ticket, pending the 100x results (if they're inline
with 10x implications), I'd be comfortable using this ticket as an opportunity
to add back the 2.2 settings commented out with some extra context for the
workloads we expect those settings to excel on and keeping G1 the default.
[~pauloricardomg]: could you elaborate on some of the pain points you ran into
with an 8G heap and G1?
> Consider reverting to CMS GC on 3.0
> -----------------------------------
>
> Key: CASSANDRA-10403
> URL: https://issues.apache.org/jira/browse/CASSANDRA-10403
> Project: Cassandra
> Issue Type: Improvement
> Components: Config
> Reporter: Joshua McKenzie
> Assignee: Paulo Motta
> Fix For: 3.0.0 rc2
>
>
> Reference discussion on CASSANDRA-7486.
> For smaller heap sizes G1 appears to have some throughput/latency issues when
> compared to CMS. With our default max heap size at 8G on 3.0, there's a
> strong argument to be made for having CMS as the default for the 3.0 release.
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