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From "Joshua McKenzie (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (CASSANDRA-10403) Consider reverting to CMS GC on 3.0
Date Wed, 30 Sep 2015 18:10:04 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-10403?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14938181#comment-14938181
] 

Joshua McKenzie edited comment on CASSANDRA-10403 at 9/30/15 6:09 PM:
----------------------------------------------------------------------

-The debate here isn't between "Do we consider G1 or disregard G1 entirely as the general
case", but rather "Do we use CMS or G1 as our default GC for 3.0, keeping the settings for
the alternative available in our configuration files for users to swap between easily".-

Edit: missed the "general case" phrase. To that point, I haven't heard of actual data showing
what the general case is for C* usage is in the wild regarding heap size. I would expect that
large heap deployments will be disproportionately reflected in the memories of people in the
field  since CMS causes pain at that point.

[~enigmacurry]: did we ever get that 100x test run to complete successfully? Before we determine
whether Paulo should go fully down this rabbit-hole pre 3.0 releasing, I'd like that data
point since we invested some effort into getting that running already.

Edit: 


was (Author: joshuamckenzie):
The debate here isn't between "Do we consider G1 or disregard G1 entirely", but rather "Do
we use CMS or G1 as our default GC for 3.0, keeping the settings for the alternative available
in our configuration files for users to swap between easily".

[~enigmacurry]: did we ever get that 100x test run to complete successfully? Before we determine
whether Paulo should go fully down this rabbit-hole pre 3.0 releasing, I'd like that data
point since we invested some effort into getting that running already.

> 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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