[
https://issues.apache.org/jira/browse/CASSANDRA-7486?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14519604#comment-14519604
]
Phil Yang commented on CASSANDRA-7486:
--------------------------------------
I think the default option should be prudence and care enough to change.
Usually for C* users, it is acceptable that there is no better performance in
new version. However, it may be unacceptable if the new version get a worse
performance. If there is risk that in some cases G1 is worse than CMS, it may
be a better choice to make G1 an optional choice first by offering another
conf/cassandra-env-g1.sh file to let people have a try and don't change the
default settings.
For the tests comparing G1 and CMS, does the tests cover some extreme case? For
example: bootstrap/rebuild/remove node, repair, lots of queries over
tombstone_failure_threshold... And I think each test should take at lease 24
hours to have several full GCs to estimate the latency.
Furthermore, now using CMS, we have a max heap size (8GB) limit even if the
memory of this node is very large. If we decide to change the default gc
algorithm, what is the suitable new limit?
> Compare CMS and G1 pause times
> ------------------------------
>
> Key: CASSANDRA-7486
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7486
> Project: Cassandra
> Issue Type: Test
> Components: Config
> Reporter: Jonathan Ellis
> Assignee: Shawn Kumar
> Fix For: 2.1.6
>
>
> See
> http://www.slideshare.net/MonicaBeckwith/garbage-first-garbage-collector-g1-7486gc-migration-to-expectations-and-advanced-tuning
> and https://twitter.com/rbranson/status/482113561431265281
> May want to default 2.1 to G1.
> 2.1 is a different animal from 2.0 after moving most of memtables off heap.
> Suspect this will help G1 even more than CMS. (NB this is off by default but
> needs to be part of the test.)
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
