There's a lot of work that's gone into G1 to the point where for almost all workloads it will perform better than CMS. However, there are almost no knobs to tune (most G1 params are "advisory" and G1 will happily ignore them if it wants to), so there may not be a great replacement if people are tuning CMS heavily for a specific workload. Can you define "friendlier" in the context of CMS?
Derek On Wed, Nov 9, 2022 at 3:10 PM Brandon Williams <dri...@gmail.com> wrote: > > If CMS is gone, is there a friendlier alternative to G1? > > On Wed, Nov 9, 2022 at 3:53 PM Josh McKenzie <jmcken...@apache.org> wrote: > > > > My recollection (and brief sleuthing now) surfaces: we've gone back and > > forth on the G1 vs. CMS debate over the years and I think we settled on "it > > all depends on your environment, workload, and you need to tune it anyway. > > It might be worth having a 'default' mode that selects one of the two based > > on heap size unless otherwise specified". > > > > I certainly wouldn't make changes to any defaults on a release between beta > > and rc personally. > > > > On Wed, Nov 9, 2022, at 4:20 PM, Jeff Jirsa wrote: > > > > G1 you can argue for with the changes in the JDK, though it's MUCH less > > friendly to small heaps (e.g. probably our default simple user). > > > > Offheap memtables are different though. If someone wants to attest that > > offheap_objects get the same level of rigorous testing as the existing > > default, that'd be useful, but I'm pretty sure that's not true, and bugs > > like https://issues.apache.org/jira/browse/CASSANDRA-12125 (which remains > > undiagnosed) reinforce that it's less commonly used and may have latent > > undiscovered bugs for default users. > > > > > > > > > > > > On Wed, Nov 9, 2022 at 11:23 AM Mick Semb Wever <m...@apache.org> wrote: > > > > Any objections to making these changes, at the very last minute, for > > 4.1-rc1 ? > > This is CASSANDRA-12029 and CASSANDRA-7486 > > > > Provided we figure out patches for them in the next day or two. > > > > -- +---------------------------------------------------------------+ | Derek Chen-Becker | | GPG Key available at https://keybase.io/dchenbecker and | | https://pgp.mit.edu/pks/lookup?search=derek%40chen-becker.org | | Fngrprnt: EB8A 6480 F0A3 C8EB C1E7 7F42 AFC5 AFEE 96E4 6ACC | +---------------------------------------------------------------+
