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Concurrency bugs are notoriously difficult to detect because there can be vast combinations of interleavings among concurrent threads, yet only a small fraction can reveal them. Atomic-set serializability characterizes a wide range of concurrency bugs, including data races and atomicity violations. In this paper, we propose a two-phase testing technique that can effectively detect atomic-set serializability violations. In Phase I, our technique infers potential violations that do not appear in a concrete execution and prunes those interleavings that are violation-free. In Phase II, our technique actively controls a thread scheduler to enumerate these potential scenarios identified in Phase I to look for real violations. We have implemented our technique as a prototype system ASSETFUZZER and applied it to a number of subject programs for evaluating concurrency defect analysis techniques. The experimental results show that ASSETFUZZER can identify more concurrency bugs than two recent testing tools RACEFUZZER and ATOMFUZZER. [ABSTRACT FROM AUTHOR]

Recent techniques for fault localization leverage code coverage to address the high cost problem of debugging. These techniques exploit the correlations between program failures and the coverage of program entities as the clue in locating faults. Experimental evidence shows that the effectiveness of these techniques can be affected adversely by coincidental correctness, which occurs when a fault is executed but no failure is detected. In this paper, we propose an approach to address this problem. We refine code coverage of test runs using control- and data-flow patterns prescribed by different fault types. We conjecture that this extra information, which we call context patterns, can strengthen the correlations between program failures and the coverage of faulty program entities, making it easier for fault localization techniques to locate the faults. To evaluate the proposed approach, we have conducted a mutation analysis on three real world programs and cross-validated the results with real faults. The experimental results consistently show that coverage refinement is effective in easing the coincidental correctness problem in fault localization techniques. [ABSTRACT FROM AUTHOR]