Efficient and Deterministic Record & Replay for Actor Languages

TL;DR

This paper introduces a low-overhead, deterministic record & replay system for actor languages, enabling effective debugging of concurrent applications with minimal performance impact.

Contribution

It presents a novel, efficient record & replay approach tailored for actor languages, addressing debugging challenges at the actor abstraction level.

Findings

Average 10% runtime overhead for tracing on benchmarks

Maximum 1% latency increase for web application HTTP requests

Trace data size of about 1.4 MB/s for production scenarios

Abstract

With the ubiquity of parallel commodity hardware, developers turn to high-level concurrency models such as the actor model to lower the complexity of concurrent software. However, debugging concurrent software is hard, especially for concurrency models with a limited set of supporting tools. Such tools often deal only with the underlying threads and locks, which is at the wrong abstraction level and may even introduce additional complexity. To improve on this situation, we present a low-overhead record & replay approach for actor languages. It allows one to debug concurrency issues deterministically based on a previously recorded trace. Our evaluation shows that the average run-time overhead for tracing on benchmarks from the Savina suite is 10% (min. 0%, max. 20%). For Acme-Air, a modern web application, we see a maximum increase of 1% in latency for HTTP requests and about 1.4 MB/s of trace data. These results are a first step towards deterministic replay debugging of actor systems in production.