In 2023, I wrote about how we’ve tuned Ruby’s garbage collector for Shopify’s monolith, including how we implemented out-of-band garbage collection to reduce the impact of major collection on latency. While the latency improvements were massive, we weren’t entirely satisfied with the heuristics used to trigger out-of-band garbage collection. It was purely based on averages, so we had to trade latency for capacity. More importantly, it didn’t fully eliminate major collection from request cycles, ...