# A Study of Concurrency Bugs and Advanced Development Support for Actor-based Programs

## TL;DR

This paper categorizes concurrency bugs in actor-based programs, analyzes their causes and behaviors, and highlights gaps in current static analysis and testing approaches, proposing directions for improved debugging support.

## Contribution

It provides a comprehensive taxonomy of actor-based concurrency bugs and identifies limitations in existing analysis methods, suggesting new debugging techniques.

## Key findings

- Current tools focus on deadlocks and protocol violations.
- Livelocks and behavioral deadlocks are under-addressed.
- Taxonomy aids in developing better debugging support.

## Abstract

The actor model is an attractive foundation for developing concurrent applications because actors are isolated concurrent entities that communicate through asynchronous messages and do not share state. Thereby, they avoid concurrency bugs such as data races, but are not immune to concurrency bugs in general. This study taxonomizes concurrency bugs in actor-based programs reported in literature. Furthermore, it analyzes the bugs to identify the patterns causing them as well as their observable behavior. Based on this taxonomy, we further analyze the literature and find that current approaches to static analysis and testing focus on communication deadlocks and message protocol violations. However, they do not provide solutions to identify livelocks and behavioral deadlocks. The insights obtained in this study can be used to improve debugging support for actor-based programs with new debugging techniques to identify the root cause of complex concurrency bugs.