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We present a technique for automatically verifying atomicity of composed concurrent operations. The main observation behind our approach is that many composed concurrent operations which occur in practice are data-independent. That is, the control-flow of the composed operation does not depend on specific input values. While verifying data-independence is undecidable in the general case, we provide succint sufficient conditions that can be used to establish a composed operation as data-independent. We show that for the common case of concurrent maps, data-independence reduces the hard problem of verifying linearizability to a verification problem that can be solved efficiently with a bounded number of keys and values.We implemented our approach in a tool called VINE and evaluated it on all composed operations from 57 real-world applications (112 composed operations). We show that many composed operations (49 out of 112) are data-independent, and automatically verify 30 of them as linearizable and the rest 19 as having violations of linearizability that could be repaired and then subsequently automatically verified. Moreover, we show that the remaining 63 operations are not linearizable, thus indicating that data independence does not limit the expressiveness of writing realistic linearizable composed operations. concurrency, linearizability, verification, composed operations, dataindependence, collections Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. . This composed operation's semantics is equivalent to attr.remove(name), however, it is more efficient in the general case due to Java's ConcurrentHashMap internal locking mechanism. Categories and Subject

The ability of modern SAT solvers to produce proofs of unsatisfiability for Boolean formulas has become a powerful tool for EDA applications. Proofs are generated from a resolve trace that captures information about the creation of all conflict clauses. Due to their sizes, resolve traces are kept in files. The sizes of these files makes the use of proofs of unsatisfiability impractical for industrial tools. Although only a small part of the resolve trace is eventually used, until now it was not known how to filter out unnecessary information.We propose a simple algorithm for on-the-fly resolve trace minimization in which we identify clauses that are guaranteed not to take part in the proof of unsatisfiability, and delete all of their associated information. This algorithm dramatically decreases the size of the resolve trace, to the point where it can be stored in the main memory. Our experiments reveal that the minimized trace is typically 3 to 6 times smaller. This makes the use of proofs of unsatisfiability and the computation of unsat cores more practical and will enable future applications to take advantage of it.

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