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https://issues.apache.org/jira/browse/CASSANDRA-7486?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14523724#comment-14523724
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Albert P Tobey commented on CASSANDRA-7486:
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I only started messing with G1 this year, so I only know the old behavior by
lore I've read and heard. I have not observed significant problems it in the
~20-40 hours I've spent tuning clusters with G1 recently.
I don't recommend anyone try G1 on JDK 7 < u75 or JDK 8 < u40 (although it's
probably OK down to u20 according to the docs I've read). I did some testing on
JDK7u75 and it was stable but didn't spend much time on it since JDK8u40 gave a
nice bump in performance (5-10% on a customer cluster) by just switching JDKs
and nothing else.
>From what I've read about the reference clearing issues, there is a new-ish
>setting to enable parallel reference collection, -XX:+ParallelRefProcEnabled.
>The advice in the docs is to only turn it on if a significant amount of time
>is spent on RefProc collection, e.g. " [Ref Proc: 5.2 ms]". I pulled that
>from a log I had handy and that is high enough that we might want to consider
>enabling the flag, but in most of my observations it hovers around 0.1ms under
>saturation load.
> 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.)
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