Memory Efficient WebAssembly Containers

Abstract

WebAssembly (Wasm) is a portable, highperformance binary instruction format originally designed for web browsers. It is rapidly gaining traction in server-side applications, including containerized environments orchestrated by Kubernetes. However, the performance impact of a widespread WebAssembly adoption in containerized environments remains unclear. Solutions relying on suboptimal WebAssembly runtimes may increase performance and memory overhead, especially in high-density deployment settings. In this paper, we explore the impact of WebAssembly runtimes on containerized application deployment in Kubernetes. Through an in-depth analysis of existing Wasm container runtimes, we identify inefficiencies in memory usage and startup times, limiting Wasm's viability in large-scale deployments. We propose a new integration of the lightweight WebAssembly Micro Runtime (WAMR) into the crun container runtime to resolve the identified inefficiencies of Wasm containers. Benchmark evaluations demonstrate that our WAMR integration reduces memory usage by 11% to 78% per container compared to existing Wasm runtimes while outperforming 4 of 6 benchmarked runtimes in container startup time. Furthermore, our integration reduces memory usage compared to Python containers by at least 16% and startup time by 3% to 18%. Our findings show that Wasm containers are a competitive alternative to traditional non-Wasm container solutions, especially in dense container deployments, and highlight the importance of runtime optimization in cloudnative environments. Our work is open-source and available at https://github.com/atlarge-research/continuum/tree/wasm.