Mirrors my experience as well. Nearly a decade of working on large Ruby/Rails apps, some with very complex reporting / data processing flows (talking like billi

Mirrors my experience as well. Nearly a decade of working on large Ruby/Rails apps, some with very complex reporting / data processing flows (talking like billions of db rows processed in streaming queries, media encoding, etc) and a particular CSV processing situation like yours was the only time I needed to manually trigger GC... and even that was just triggering it, not even tweaking it. The defaults seem very good, even at scale.