Supervisory Control of Software Execution for Failure Avoidance: Experience from the Gadara Project

Abstract

Abstract:We discuss our experience in the Gadara project, whose objective is to control the execution of software to avoid potential failures using discrete-event control techniques. We summarize our accomplishments so far and discuss future challenges. After initial work on safety of workflow scripts via supervisory control techniques, we have focused our efforts on deadlock avoidance in multithreaded C programs that use locking primitives to control access to shared data. We describe how we automatically construct automata models of workflows and Petri net models of concurrent programs. In the case of multithreaded C programs, the resulting models characterize a new class of resource-allocation Petri nets called Gadara nets. These nets enjoy structural properties that facilitate the synthesis of liveness-enforcing control policies that are maximally-permissive. We describe our strategy for run-time implementation of these control policies, especially by a technique known as code instrumentation. It is hoped that the lessons learned so far in the Gadara project will be useful in other application areas and will suggest avenues for future theoretical investigations.

The role of supervisory controller synthesis in automatic control software development

“…A supervisor, based on automatically extracted software models, can constrain software behavior to prevent runtime failures. Theory and tools for deadlock avoidance by supervision in concurrent programming are still being developed, but experiments show seamless elimination of common deadlock occurrences, while merely doubling compile time [36,37].…”

Logico-numerical control for software components reconfiguration

“…In the area of DES modeling and synthesis techniques, applications to the control of computing systems is still quite recent, and has been explored for example on problems like the deadlock avoidance in multi-thread programs running on multi-core processor architectures [19,20]. Other works, e.g., by Hajjar et al [21], target especially the control of software components where verification and controller synthesis are combined for the construction of assemblies of reusable Commercial off-the-shelf (COTS) components.…”

Feedback Control as MAPE-K Loop in Autonomic Computing

“…[63] is a programming language-level approach, that and relies upon Petri net formal models, where control logic is synthesized, in the form of additional control places in the Petri nets, in order to inhibit behaviors leading to interlocking. The Gadara project elaborates on these topics [62]. They apply Discrete Control internally to the compilation, only for deadlock avoidance, in a way independent of the application.…”