629 research outputs found
Sound Static Deadlock Analysis for C/Pthreads (Extended Version)
We present a static deadlock analysis approach for C/pthreads. The design of
our method has been guided by the requirement to analyse real-world code. Our
approach is sound (i.e., misses no deadlocks) for programs that have defined
behaviour according to the C standard, and precise enough to prove
deadlock-freedom for a large number of programs. The method consists of a
pipeline of several analyses that build on a new context- and thread-sensitive
abstract interpretation framework. We further present a lightweight dependency
analysis to identify statements relevant to deadlock analysis and thus speed up
the overall analysis. In our experimental evaluation, we succeeded to prove
deadlock-freedom for 262 programs from the Debian GNU/Linux distribution with
in total 2.6 MLOC in less than 11 hours
Dynamic Race Prediction in Linear Time
Writing reliable concurrent software remains a huge challenge for today's
programmers. Programmers rarely reason about their code by explicitly
considering different possible inter-leavings of its execution. We consider the
problem of detecting data races from individual executions in a sound manner.
The classical approach to solving this problem has been to use Lamport's
happens-before (HB) relation. Until now HB remains the only approach that runs
in linear time. Previous efforts in improving over HB such as causally-precedes
(CP) and maximal causal models fall short due to the fact that they are not
implementable efficiently and hence have to compromise on their race detecting
ability by limiting their techniques to bounded sized fragments of the
execution. We present a new relation weak-causally-precedes (WCP) that is
provably better than CP in terms of being able to detect more races, while
still remaining sound. Moreover it admits a linear time algorithm which works
on the entire execution without having to fragment it.Comment: 22 pages, 8 figures, 1 algorithm, 1 tabl
Static deadlock detection for concurrent go by global session graph synthesis
© 2016 ACM.Go is a programming language developed at Google, with channelbased concurrent features based on CSP. Go can detect global communication deadlocks at runtime when all threads of execution are blocked, but deadlocks in other paths of execution could be undetected. We present a new static analyser for concurrent Go code to find potential communication errors such as communication mismatch and deadlocks at compile time. Our tool extracts the communication operations as session types, which are then converted into Communicating Finite State Machines (CFSMs). Finally, we apply a recent theoretical result on choreography synthesis to generate a global graph representing the overall communication pattern of a concurrent program. If the synthesis is successful, then the program is free from communication errors. We have implemented the technique in a tool, and applied it to analyse common Go concurrency patterns and an open source application with over 700 lines of code
Strong Memory Consistency For Parallel Programming
Correctly synchronizing multithreaded programs is challenging, and errors can lead to program failures (e.g., atomicity violations). Existing memory consistency models rule out some possible failures, but are limited by depending on subtle programmer-defined locking code and by providing unintuitive semantics for incorrectly synchronized code. Stronger memory consistency models assist programmers by providing them with easier-to-understand semantics with regard to memory access interleavings in parallel code. This dissertation proposes a new strong memory consistency model based on ordering-free regions (OFRs), which are spans of dynamic instructions between consecutive ordering constructs (e.g. barriers). Atomicity over ordering-free
regions provides stronger atomicity than existing strong memory consistency models with competitive performance. Ordering-free regions also simplify programmer reasoning by limiting the potential for atomicity violations to fewer points in the program’s execution. This dissertation explores both software-only and hardware-supported systems that provide OFR serializability
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