Deadlocks can have devastating effects in systems code. We have developed a type and effect system that provably avoids them and in this paper we present a tool that uses a sound static analysis to instrument multithreaded C programs and then links these programs with a run-time system that avoids possible deadlocks. In contrast to most other purely static tools for deadlock freedom, our tool does not insist that programs adhere to a strict lock acquisition order or use lock primitives in a block-structured way, thus it is appropriate for systems code and OS applications. We also report some very promising benchmark results which show that all possible deadlocks can automatically be avoided with only a small run-time overhead. More importantly, this is done without having to modify the original source program by altering the order of resource acquisition operations or by adding annotations.
A challenge for programming language research is to design and implement multi-threaded low-level languages providing static guarantees for memory safety and freedom from data races. Towards this goal, we sketch a concurrent language employing safe region-based memory management and hierarchical locking of regions. Both regions and locks are treated uniformly, and the language supports ownership transfer, early deallocation of regions and early release of locks in a safe manner.
Deadlocks occur in concurrent programs as a consequence of cyclic resource acquisition between threads. In this paper we present a novel type system that guarantees deadlock freedom for a language with references, unstructured locking primitives, and locks which are implicitly associated with references. The proposed type system does not impose a strict lock acquisition order and thus increases programming language expressiveness
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