fwiw, the "CMS is friendlier for small heaps with C*" conclusion may no longer be accurate; a lot of work has gone into G1 since the last time we've covered the topic as a project. Nevermind the changes in C*.
Lots of moving targets. On Wed, Nov 9, 2022, at 6:13 PM, Brad wrote: > The default garbage collector in Java 11 is G1*. *It's designed to be > self-tuning, so I'd call it friendly. We have run Java 8 and 11 on G1 in > production on all of our 1,000+ clusters for several years. > > I'd agree with Jeremiah that it's worth changing in trunk at the very least > and consider backporting. > > On Wed, Nov 9, 2022 at 5:10 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. >> > >> >
