We propose a new method for dynamically generating likely invariants from multithreaded programs.While existing invariant generation tools work well on sequential programs, they are ineffective at reasoning about multithreaded programs both in terms of the number of real invariants generated and in terms of their usefulness in helping programmers. We address this issue by developing a new dynamic invariant generator consisting of an LLVM based code instrumentation front end, a systematic thread interleaving explorer, and a customized invariant inference engine. We show that efficient interleaving exploration strategies can be used to generate a diversified set of executions with little runtime overhead. Furthermore, we show that focusing on a small subset of thread-local transition invariants is often sufficient for reasoning about the concurrency behavior of programs. We have evaluated our new method on a set of open-source multithreaded C/C++ benchmarks. Our experiments show that our method can generate invariants that are significantly higher in quality than the previous state-of-the-art.

We propose a new method for runtime checking of a relaxed consistency property called quasi linearizability for concurrent data structures.Quasi linearizability generalizes the standard notion of linearizability by introducing nondeterminism into the parallel computations quantitatively and then exploiting such nondeterminism to improve the runtime performance. However, ensuring the quantitative aspects of this correctness condition in the low-level code of the concurrent data structure implementation is a difficult task.Our runtime verification method is the first fully automated method for checking quasi linearizability in the C/C++ code of concurrent data structures. It guarantees that all the reported quasi linearizability violations manifested by the concurrent executions are real violations. We have implemented our method in a software tool based on the LLVM compiler and a systematic concurrency testing tool called Inspect. Our experimental evaluation shows that the new method is effective in detecting quasi linearizability violations in the source code implementations of concurrent data structures.

We propose a new method for runtime checking of a relaxed consistency property called quasi linearizability for concurrent data structures. Quasi linearizability generalizes the standard notion of linearizability by intentionally introducing nondeterminism into the parallel computations and exploiting such nondeterminism to improve the performance. However, ensuring the quantitative aspects of this correctness condition in the low level code is a difficult task. Our method is the first fully automated method for checking quasi linearizability in the unmodified C/C++ code of concurrent data structures. It guarantees that all the reported quasi linearizability violations are real violations. We have implemented our method in a software tool based on LLVM and a concurrency testing tool called Inspect. Our experimental evaluation shows that the new method is effective in detecting quasi linearizability violations in the source code of concurrent data structures.