Type-Based Deadlock-Freedom Verification for Non-Block-Structured Lock Primitives and Mutable References

Abstract

Abstract. We present a type-based deadlock-freedom verification for concurrent programs with non-block-structured lock primitives and mutable references. Though those two features are frequently used, they are not dealt with in a sufficient manner by previous verification methods. Our type system uses a novel combination of lock levels, obligations and ownerships. Lock levels are used to guarantee that locks are acquired in a specific order. Obligations and ownerships guarantee that an acquired lock is released exactly once.

Deadlock Analysis of Concurrent Objects: Theory and Practice

“…On the contrary, our technique does not compute any ordering of locks, thus being more flexible: a computation may acquire two locks in different order at different stages, being correct in our case, but incorrect with the other techniques. In [18,21,22], Kobayashi and his colleagues use a very powerful technique, since they do not commit to any predefined partial order of locks and apply to codes with dynamic structures. However their concurrency models are different from that of ABS and a precise comparison is a matter for future work.…”

Safe Locking for Multi-threaded Java

“…Their language, a variant of the λ -calculus, however, is sequential. [15] uses a type and effect system to assure deadlock freedom in a calculus quite similar to ours in that it supports thread based concurrency and a shared mutable heap. On the surface, the paper deals with a different problem (deadlock freedom) but as part of that it treats the same problem as we, namely to avoind releasing free locks or locks not owned, and furthermore,…”

“…The language of [15] is more low-level in that it supports pointer dereferencing, whereas our object-oriented calculus allows shared access on mutable storage only for the fields of objects and especially we do not allow pointer dereferencing. Pointer dereferencing makes the static analysis more complex as it needs to keep track of which thread is actually responsible for lock-releasing in terms of read and write permissions.…”

“…In a way, the content of a local variable is "owned" by a thread; therefore there is no need to track the current owner across different threads to avoid bad interference. Besides that, our analysis can handle re-entrant locks, which are common in object-oriented languages such as Java or C , whereas [15] covers only binary locks. The same restriction applies to [16], which represents a type system assuring race-freedom.…”

Analysis of Deadlocks in Object Groups

“…The proposals for statically analyzing deadlocks are largely based on types [12,22,21,23]. Some work also addresses deadlocks in object-oriented programs [1,2].…”