You seem to imply that everything they run is Ruby, but they're talking about 2.4 million CPU cores on their K8s cluster, where maybe other stuff runs as well, like their Kafka clusters [1] and Airflow [2]?

[1] https://shopify.engineering/running-apache-kafka-on-kubernet...

[2] https://shopify.engineering/lessons-learned-apache-airflow-s...