It came in with PE 2019.0 and Java 11. Basically, after performance testing, we found that: • ParallelGC can reduce the maximum heap size below

-Xmx

when appropriate, which frees RAM for use by other part of the system (GC may have gained this capability by Java 17). • G1 does not fit well with JRuby: https://github.com/jruby/jruby/issues/5789