one thing we observed was to set gc config to

-Xms24G -Xmx24G -XX:+UseG1GC -XX:MaxGCPauseMillis=20 -XX:+ParallelRefProcEnabled -XX:+DisableExplicitGC -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintGCApplicationStoppedTime -XX:+PrintGCApplicationConcurrentTime -Xloggc:/opt/pinot/gc-pinot-server.log

Also, I got an "uncrecognized option PrintGCDateStamps" - I think that's for java8, changed the logging options to:

-Xlog:safepoint
-Xlog:gc*
-Xlog:::time,level,tags