Advancing Performance via a Systematic Application of Research and Industrial Best Practice

An elusive facet of high-impact research is translation to production. Production deployments are intrinsically complex and specialized, whereas research exploration requires stripping away incidental complexity and extraneous requirements to create clarity and generality. Conventional wisdom suggests that promising research rarely holds up once simplifying assumptions and missing features are addressed. This paper describes a productization methodology that led to a striking result: outperforming the mature and highly optimized state of the art by more than 10%.

Concretely, this experience paper captures lessons from translating a high-performance research garbage collector published at PLDI'22, called LXR, to a hyperscale revenue-critical application. Key to our success was a new process that dovetails best practice research methodology with industrial processes, at each step assuring that neither research metrics nor production measures regressed. This paper makes three contributions. i) We advance the state of the art, nearly halving the cost of garbage collection. ii) We advance research translation by sharing our approach and five actionable lessons. iii) We pose questions about how the community should evaluate innovative ideas in mature and heavily productized fields.

We deliver an optimized version of LXR. This collector, as far as we are aware, is the fastest generalpurpose garbage collector for Java to date. On standard workloads, it substantially outperforms OpenJDK's default G1 collector and the prior version of LXR, while also meeting Google internal correctness and uptime requirements. We address all of the limitations identified in the PLDI'22 paper. We use this experience to illustrate the following key lessons that are concrete, actionable, and transferable. L1) A systematic combination of research and production methodologies can meet production objectives while simultaneously advancing the research state-of-the-art. L2) A benchmark suite cannot and need not contain facsimiles of production workloads. It is sufficient to replicate individual pathologies that manifest in production (e.g., allocation rates, trace rates, heap constraints, etc.) or configure the JVM to force a workload to manifest the pathology. L3) Productization experiences can strengthen research workloads; we upstreamed one such workload. L4) Production environment requirements are myriad and sometimes prosaic, extending well beyond those that can reasonably be addressed in a research paper. L5) This collector is not yet in production, reminding us that replacing core technology in industry is a challenging sociotechnical problem.

The artifact we deliver gives practitioners and researchers a new benchmark for high performance garbage collection. The lessons we enumerate should help academic and industrial researchers with actionable steps to close the gap between research paper results and industrial impact. The 10% 'productization dividend' the process delivered should spark discussion about how our field evaluates innovative ideas in mature areas.

• Work done while employed by Google Australia.