Schedule Analysis of Concurrent Logic Programs

A compilation technique is proposed for concurrent logic programs called schedule analysis. Schedule analysis deduces at compile-time a partial schedule for the processes of a program by partitioning the atoms of each clause into threads. Threads are totally ordered sets of atoms whose relative ordering is determined by a scheduler. Threads reduce scheduler activity and permit a wealth of traditional Prolog optimisations to be applied to the program. A framework for schedule analysis is proposed and this defines a procedure for creating threads. A safety result is presented stating the conditions under which the work of the scheduler can be reduced from ordering processes to ordering threads. Schedule analysis has been integrated into a compiler and implementation has suggested that it can play a central role in compilation. Optimisations which follow from schedule analysis include a reduction in scheduling, the removal of synchronisation checks, the simplification of unification, decreased garbage collection and a reduction in argument copying

Reachability and Termination Analysis of Concurrent Quantum Programs

We introduce a Markov chain model of concurrent quantum programs. This model is a quantum generalization of Hart, Sharir and Pnueli's probabilistic concurrent programs. Some characterizations of the reachable space, uniformly repeatedly reachable space and termination of a concurrent quantum program are derived by the analysis of their mathematical structures. Based on these characterizations, algorithms for computing the reachable space and uniformly repeatedly reachable space and for deciding the termination are given.Comment: Accepted by Concur'12. Comments are welcom

The CIAO multiparadigm compiler and system: A progress report

Abstract is not available

Logical Concurrency Control from Sequential Proofs

We are interested in identifying and enforcing the isolation requirements of a concurrent program, i.e., concurrency control that ensures that the program meets its specification. The thesis of this paper is that this can be done systematically starting from a sequential proof, i.e., a proof of correctness of the program in the absence of concurrent interleavings. We illustrate our thesis by presenting a solution to the problem of making a sequential library thread-safe for concurrent clients. We consider a sequential library annotated with assertions along with a proof that these assertions hold in a sequential execution. We show how we can use the proof to derive concurrency control that ensures that any execution of the library methods, when invoked by concurrent clients, satisfies the same assertions. We also present an extension to guarantee that the library methods are linearizable or atomic

The CIAO Multi-Dialect Compiler and System: An Experimentation Workbench for Future (C)LP Systems

CIAO is an advanced programming environment supporting Logic and Constraint programming. It offers a simple concurrent kernel on top of which declarative and non-declarative extensions are added via librarles. Librarles are available for supporting the ISOProlog standard, several constraint domains, functional and higher order programming, concurrent and distributed programming, internet programming, and others. The source language allows declaring properties of predicates via assertions, including types and modes. Such properties are checked at compile-time or at run-time. The compiler and system architecture are designed to natively support modular global analysis, with the two objectives of proving properties in assertions and performing program optimizations, including transparently exploiting parallelism in programs. The purpose of this paper is to report on recent progress made in the context of the CIAO system, with special emphasis on the capabilities of the compiler, the techniques used for supporting such capabilities, and the results in the áreas of program analysis and transformation already obtained with the system