[
https://issues.apache.org/jira/browse/CASSANDRA-7486?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14523593#comment-14523593
]
Albert P Tobey commented on CASSANDRA-7486:
-------------------------------------------
"if I am reading correctly there was pretty never an old generation collection
under the workload I looked at. The old gen was growing but never reached the
point it needed to do an old gen GC."
^ G1 doesn't work that way.
"Another behavior to consider is worst case pause time when there is
fragmentation."
^ G1 performs compaction. It's fairly easy to trigger and observe in gc.log
with Cassandra 2.0. It takes more work with 2.1 since it seems to be easier on
the GC.
I'll see if I can find some time to generate graphs to make all this more
convincing, but time is short because I'm spending all of my time tuning users'
clusters where the #1 first issue every time is getting CMS to behave.
> 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.x
>
>
> 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)
