Nuka: A Generic Engine with Millisecond Initialization for Serverless Computing

摘要

Serverless computing is becoming one of the mainstream trends in cloud computing due to its advantages of simplified programming and cost saving. However, existing serverless platforms still adopt Docker container as its execution engine, which has the cold start problem and causes high common-case invocation latency. In this work, we analyze the lifecycle of common-case serverless invocation on existing serverless platforms and find that current container startup and pulling remote images are the two main reasons causing cold start so slow. Based on the study, we implement Nuka, a generic engine with millisecond initialization for serverless computing. Nuka is fully compatible with Docker interface and can smoothly re-place Docker as the execution engine of existing serverless plat-forms. Through the isolation pool that reuses Linux’s isolation configurations, Nuka avoids the high cost of container startup’s scalability bottleneck, which reduces container’s startup time with high concurrency scale. Nuka also avoids pulling remote images through dynamically resolving and importing required software packages from local package caching. A self-adaptive container reuse strategy dynamically controls container's pause time and replica numbers, which effectively reduces the frequency of cold start. Compared with Docker, Nuka can get a millisecond initialization with high concurrency and significantly reduces average time cost of cold startup by 6× on existing serverless platforms.