A Concurrency-Agnostic Protocol for Multi-Paradigm Concurrent Debugging Tools

Today’s complex software systems combine high-level con- currency models. Each model is used to solve a specific set of problems. Unfortunately, debuggers support only the low- level notions of threads and shared memory, forcing devel- opers to reason about these notions instead of the high-level concurrency models they chose. This paper proposes a concurrency-agnostic debugger protocol that decouples the debugger from the concurrency models employed by the target application. As a result, the underlying language runtime can define custom breakpoints, stepping operations, and execution events for each concur- rency model it supports, and a debugger can expose them without having to be specifically adapted. We evaluated the generality of the protocol by applying it to SOM ns , a Newspeak implementation, which supports a diversity of concurrency models including communicating sequential processes, communicating event loops, threads and locks, fork/join parallelism, and software transactional memory. We implemented 21 breakpoints and 20 stepping operations for these concurrency models. For none of these, the debugger needed to be changed. Furthermore, we visu- alize all concurrent interactions independently of a specific concurrency model. To show that tooling for a specific con- currency model is possible, we visualize actor turns and message sends separately.