+1 to switching to G1 as well. Most production clusters I've seen are typically running with a heap size of 16 GB or higher which works well with G1.
I agree with Elliott's comment; I think this change should go into 4.1 onwards (i.e. no change to the default JVM settings in 4.0). On Fri, 11 Nov 2022 at 08:50, Mick Semb Wever <m...@apache.org> wrote: > In case of GC, reasonably extensive performance testing should be the >> expectations. Potentially revisiting some of the G1 params for the 4.1 >> reality - quite a lot has changed since those optional defaults where >> picked. >> > > > I've put our battle-tested g1 opts (from consultants at TLP and DataStax) > in the patch for CASSANDRA-18027 > > In reality it is really not much of a change, g1 does make it simple. > Picking the correct ParallelGCThreads and ConcGCThreads and the floor to > the new heap (XX:NewSize) is still required, though we could do a much > better job of dynamic defaults to them. > > Alex Dejanovski's blog is a starting point: > https://thelastpickle.com/blog/2020/06/29/cassandra_4-0_garbage_collectors_performance_benchmarks.html > where this gc opt set was used (though it doesn't prove why those options > are chosen) > > The bar for objection to sneaking these into 4.1 was intended to be low, > and I stand by those that raise concerns. > >
