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Grove is a concurrent separation logic library for verifying distributed systems. Grove is the first to handle time-based leases, including their interaction with reconfiguration, crash recovery, thread-level concurrency, and unreliable networks. This paper uses Grove to verify several distributed system components written in Go, including GroveKV, a realistic distributed multi-threaded key-value store. GroveKV supports reconfiguration, primary/backup replication, and crash recovery, and uses leases to execute read-only requests on any replica. GroveKV achieves high performance (67-73% of Redis on a single core), scales with more cores and more backup replicas (achieving about 2× the throughput when going from 1 to 3 servers), and can safely execute reads while reconfiguring. 

Multi-version concurrency control (MVCC) is a widely used, sophisticated approach for handling concurrent transactions. vMVCC is the first MVCC-based transaction library that comes with a machine-checked proof of correctness, providing clients with a guarantee that it will correctly handle all transactions despite a complicated design and implementation that might otherwise be error-prone. vMVCC is implemented in Go, stores data in memory, and uses several optimizations, such as RDTSC-based timestamps, to achieve high performance (25–96% the throughput of Silo, a state-of-the-art in-memory database, for YCSB and TPC-C workloads). Formally specifying and verifying vMVCC required adopting advanced proof techniques, such as logical atomicity and prophecy variables, owing to the fact that MVCC transactions can linearize at timestamp generation prior to transaction execution. 

The main contribution of this paper is GoJournal, a verified, concurrent journaling system that provides atomicity for storage applications, together with Perennial 2.0, a framework for formally specifying and verifying concurrent crash-safe systems. GoJournal’s goal is to bring the advantages of journaling for code to specs and proofs. Perennial 2.0 makes this possible by introducing several techniques to formalize GoJournal’s specification and to manage the complexity in the proof of GoJournal’s implementation. Lifting predicates and crash framing make the specification easy to use for developers, and logically atomic crash specifications allow for modular reasoning in GoJournal, making the proof tractable despite complex concurrency and crash interleavings. GoJournal is implemented in Go, and Perennial is implemented in the Coq proof assistant. While verifying GoJournal, we found one serious concurrency bug, even though GoJournal has many unit tests. We built a functional NFSv3 server, called GoNFS, to use GoJournal. Performance experiments show that GoNFS provides similar performance (e.g., at least 90% throughput across several benchmarks on an NVMe disk) to Linux’s NFS server exporting an ext4 file system, suggesting that GoJournal is a competitive journaling system. We also verified a simple NFS server using GoJournal’s specs, which confirms that they are helpful for application verification: a significant part of the proof doesn’t have to consider concurrency and crashes.