80% faster, 70% less memory: Go tricks we used to build a high-performance Prometheus query engine

Description

Speakers: Charles Korn and Jon Kartago Lamida We’ve been building a brand-new, Prometheus-compatible query engine from the ground up for Grafana Mimir in Go. Our new query engine has been designed to deliver an improved user experience and vastly improved performance: our benchmarks show queries running up to 80% faster and with 70% lower peak memory consumption than Prometheus’ default engine, and our real-world testing shows similar results. As we’ve been building the engine, we’ve learnt a number of Go performance lessons the hard way, including why using byte slices can sometimes be preferable to strings, the benefits and costs of memory pooling and the surprisingly large impact of function pointers. And we’ve seen the complexity (and bugs!) these things can introduce too, and developed a number of techniques to help combat this.