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Paulo Motta commented on CASSANDRA-10403:
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bq. So, tests that go up to 32G of heap on a system with 64GB of main memory
are really where the proof points are. Saturating loads are good too.
As far as I understood the purpose of this ticket is to evaluate whether it
makes sense to ship 3.0 with G1 (considering a default heap size of 8GB), so we
should limit the heap experiments to 8GB heap size. If this understanding is
correct, it's out of the scope of this ticket to re-evaluate the default heap
size, or provide dynamic heap/gc settings based (although it will be nice to
perform more thorough experiments and add support to dynamic profiles in a
separate ticket after GA). For this reason I opted for m1.xlarge instances,
which is the equivalent of a m3.xlarge, which is the smallest instance someone
would deploy C* on production, but with disks to create additional heap
pressure due to I/O exhaustion.
We are quite confident G1 is better for heaps > 24GB, but the question we want
to answer on this ticket is: is G1 the best option for a default 8GB heap?
Given this, do you think it's still valid to perform these experiments on an
m1.xlarge?
> 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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