Improving the Construction of Correct Distributed Systems

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Enterprises, large and small, are taking advantage of the flexibility and capacity of massive data centers (the cloud) for their infrastructure. Data centers, however, depends critically on the correct function of many complex distributed systems to realize scalable and fault-tolerant services. Unfortunately, these systems are notoriously difficult to engineer and bugs may be subtle and have catastrophic consequences. For example, in 2017 a bug in Amazon's S3 storage system caused $150 million of dollars in damage for the companies that rely on Amazon AWS services.******My research program will improve how engineers construct distributed systems, helping to debug existing systems and to design more correct future systems.I will accomplish this by devising new formal methods techniques and new tools that work on real systems, find more bugs, and are easier to use than existing approaches. My program focus has two strands:******Hybrid model checking of existing distributed systems. To help developers find bugs in existing systems I will develop techniques to combine the speed of abstract model checkers with the correctness and ease-of-use of concrete model checkers to build a hybrid model checker. My approach will use a concrete model checker to generate logs from real executions of the system. These logs will be used to construct an abstract model of the system that can be checked using an abstract model checker. Property violations, or bugs, will be verified using new distributed trace replay techniques. In concert these techniques will check more of the distributed system state space and find bugs faster.******Compiling distributed systems from specifications. To help developers construct correct new systems I will develop a compiler that translates a verified specification into a fully functioning implementation. This compiler will automate today's manual translation process, which may introduce errors and also requires substantial time and effort. This will encouraging designers to write more formal specifications for their systems. The compiler will also preserving the semantics of the specification and thereby the correctness properties. This will increase developers' confidence in the correctness of their system implementations.******The above two approaches will generate several kinds of new scientific knowledge bout the modeling of distributed systems, compilation of distributed logic, distributed state space reduction and exploration heuristics, and instrumentation and replay of distributed executions. My team and I will work to integrate this new knowledge into robust open source tools. These tools can then be used by industry practitioners to improve the correctness of existing and future distributed systems.**