Deciding Serializability in Network Systems

TL;DR

This paper introduces the SER modeling language and an automated decision procedure to verify serializability in network systems, effectively handling complex, real-world concurrent programs.

Contribution

It presents the first end-to-end automated method for serializability verification that produces certificates or counterexamples, with optimizations for scalability.

Findings

Successfully verifies serializability of real-world network programs

Reduces serializability checking to Petri net reachability queries

Handles unbounded concurrency with practical efficiency

Abstract

We present the SER modeling language for automatically verifying serializability of concurrent programs, i.e., whether every concurrent execution of the program is equivalent to some serial execution. SER programs are suitably restricted to make this problem decidable, while still allowing for an unbounded number of concurrent threads of execution, each potentially running for an unbounded number of steps. Building on prior theoretical results, we give the first automated end-to-end decision procedure that either proves serializability by producing a checkable certificate, or refutes it by producing a counterexample trace. We also present a network-system abstraction to which SER programs compile. Our decision procedure then reduces serializability in this setting to a Petri net reachability query. Furthermore, in order to scale, we curtail the search space via multiple optimizations, including Petri net slicing, semilinear-set compression, and Presburger-formula manipulation. We extensively evaluate our framework and show that, despite the theoretical hardness of the problem, it can successfully handle various models of real-world programs, including stateful firewalls, BGP routers, and more.