Multiverse Debugging: Non-deterministic Debugging for Non-deterministic Programs

Carmen Torres Lopez, Robbert Gurdeep Singh, Stefan Marr, Elisa Gonzalez Boix, Christophe Scholliers

Research output: Unpublished contribution to conferencePoster


Many of today’s software systems are parallel or concurrent. With the rise of Node.js and more generally event-loop architectures, many systems need to handle concurrency. However, its nondeterministic behavior makes it hard to reproduce bugs. Today’s interactive debuggers unfortunately do not support developers in debugging non-deterministic issues. They only allow us to explore a single execution path. Therefore, some bugs may never be reproduced in the debugging session, because the right conditions are not triggered. As a solution, we propose multiverse debugging, a new approach for debugging non-deterministic programs that allows developers to observe all possible execution paths of a parallel program and debug it interactively. We introduce the concepts of multiverse breakpoints and stepping, which can halt a program in different execution paths, i.e. universes. We apply multiverse debugging to AmbientTalk, an actor-based language, resulting in Voyager, a multiverse debugger implemented on top of the AmbientTalk operational semantics. We provide a proof of non-interference, i.e., we prove that observing the behavior of a program by the debugger does not affect the behavior of that program and vice versa. Multiverse debugging establishes the foundation for debugging non-deterministic programs interactively, which we believe can aid the development of parallel and concurrent systems.

Original languageEnglish
Publication statusPublished - 1 Jul 2019
Event33rd European Conference on Object-Oriented Programming - Hammersmith, London, United Kingdom
Duration: 15 Jul 201919 Jul 2019


Conference33rd European Conference on Object-Oriented Programming
Abbreviated titleECOOP 2019
CountryUnited Kingdom
Internet address


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