> > 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.
