GoTxn: Verifying a Crash-Safe, Concurrent Transaction System

Abstract

Bugs related to concurrency and crash safety are infamous for being subtle and hard to reproduce. Formal verification provides a way to combat such bugs through the use of machine-checked proofs about program behavior. However, reasoning about concurrency and crashes can be tricky, especially when scaling up to larger systems that must also have good performance.

This thesis discusses the verification of GoTxn, the concurrent, crash-safe transaction system underlying the verified Network File System (NFS) server DaisyNFS. It focuses on the specification and proof of the write-ahead log and the automatic two-phase locking interface used to enforce crash and concurrent atomicity in transactions, detailing how the verification framework Perennial can be used to manage assertions about crash behavior across multiple threads. By effectively harnessing concurrency to hide disk access latency, GoTxn enables performance in DaisyNFS similar to the unverified Linux NFS server.