On scaling dynamic programming problems with a multithreaded tabling Prolog system

Areias, Miguel; Rocha, Ricardo

doi:10.1016/j.jss.2016.06.060

Cited by 6 publications

(7 citation statements)

References 24 publications

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“…17,18 One such approach is the subgoal sharing with shared completed answers design. 26 The idea is as follows. The subgoal trie structures are shared among all threads, and the leaf data structures representing each tabled subgoal call C i , instead of pointing to a single subgoal frame, point to a chain of private subgoal frames, one per thread that is evaluating the call C i .…”

Section: Multithreaded Tablingmentioning

confidence: 99%

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Multi‐dimensional lock‐free arrays for multithreaded mode‐directed tabling in Prolog

Areias

Rocha

2018

Concurrency and Computation

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Summary This work proposes a new design for the supporting data structures used to implement multithreaded tabling in Prolog systems. Tabling is an implementation technique that improves the expressiveness of traditional Prolog systems in dealing with recursion and redundant computations. Mode‐directed tabling is an extension to the tabling technique that supports the definition of alternative criteria for specifying how answers are aggregated, thus being very suitable for problems where the goal is to dynamically calculate optimal or selective answers. In this work, we leverage the intrinsic potential that mode‐directed tabling has to express dynamic programming problems by creating a new design that improves the representation of multi‐dimensional arrays in the context of multithreaded tabling. To do so, we introduce a new mode for indexing arguments in mode‐directed tabled evaluations, named dim, where each dim argument features a uni‐dimensional lock‐free array. Experimental results using well‐known dynamic programming problems on a 32‐core machine show that the new design introduces less overheads and clearly improves the execution time for sequential and multithreaded tabled evaluations.

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Section: Multithreaded Tablingmentioning

confidence: 99%

“…For a tabled evaluation, a thread views its tables as private, but at the engine level, parts of the table space can be shared among threads . One such approach is the subgoal sharing with shared completed answers design . The idea is as follows.…”

Section: Introductionmentioning

confidence: 99%

Multi‐dimensional lock‐free arrays for multithreaded mode‐directed tabling in Prolog

Areias

Rocha

2018

Concurrency and Computation

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“…In this subsection, we show how dynamic programming problems fit well with concurrent tabled evaluation (Areias and Rocha 2017). To do so, we used two wellknown dynamic programming problems, the Knapsack and the Longest Common Subsequence (LCS) problems.…”

Section: Experiments On Dynamic Programming Problemsmentioning

confidence: 99%

“…Full details regarding the Prolog code fragments implementing both approaches can be found in(Areias and Rocha 2017). https://www.cambridge.org/core/terms.…”

mentioning

confidence: 99%

Table space designs for implicit and explicit concurrent tabled evaluation

Areias¹,

Rocha²

2018

Theory and Practice of Logic Programming

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One of the main advantages of Prolog is its potential for the implicit exploitation of parallelism and, as a high-level language, Prolog is also often used as a means to explicitly control concurrent tasks. Tabling is a powerful implementation technique that overcomes some limitations of traditional Prolog systems in dealing with recursion and redundant subcomputations. Given these advantages, the question that arises is if tabling has also the potential for the exploitation of concurrency/parallelism. On one hand, tabling still exploits a search space as traditional Prolog but, on the other hand, the concurrent model of tabling is necessarily far more complex, since it also introduces concurrency on the access to the tables. In this paper, we summarize Yap's main contributions to concurrent tabled evaluation and we describe the design and implementation challenges of several alternative table space designs for implicit and explicit concurrent tabled evaluation that represent different tradeoffs between concurrency and memory usage. We also motivate for the advantages of using fixed-size and lock-free data structures, elaborate on the key role that the engine's memory allocator plays on such environments, and discuss how Yap's mode-directed tabling support can be extended to concurrent evaluation. Finally, we present our future perspectives toward an efficient and novel concurrent framework which integrates both implicit and explicit concurrent tabled evaluation in a single Prolog engine.

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“…One such feature is the ISO Prolog multithreading standardization proposal [36], which currently is implemented in several Prolog systems, including Ciao, SWI Prolog, XSB Prolog and YAP Prolog, providing a highly portable solution given the number of operating systems supported by these systems. Arguably, one of the features that promises to have a significant impact is the combination of multithreading with tabling [37,38], as Prolog users will be able to exploit the combination of a higher procedural control with higher declarative semantics. Future work plans include the extension of YAPTBE to support the execution and output analysis of standard and tabled multithreaded Prolog runs.…”

Section: Further Workmentioning

confidence: 99%

On the Implementation of a Cloud-Based Computing Test Bench Environment for Prolog Systems

2017

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Software testing and benchmarking are key components of the software development process. Nowadays, a good practice in large software projects is the continuous integration (CI) software development technique. The key idea of CI is to let developers integrate their work as they produce it, instead of performing the integration at the end of each software module. In this paper, we extend a previous work on a benchmark suite for the YAP Prolog system, and we propose a fully automated test bench environment for Prolog systems, named Yet Another Prolog Test Bench Environment (YAPTBE), aimed to assist developers in the development and CI of Prolog systems. YAPTBE is based on a cloud computing architecture and relies on the Jenkins framework as well as a new Jenkins plugin to manage the underlying infrastructure. We present the key design and implementation aspects of YAPTBE and show its most important features, such as its graphical user interface (GUI) and the automated process that builds and runs Prolog systems and benchmarks.

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On scaling dynamic programming problems with a multithreaded tabling Prolog system

Cited by 6 publications

References 24 publications

Multi‐dimensional lock‐free arrays for multithreaded mode‐directed tabling in Prolog

Multi‐dimensional lock‐free arrays for multithreaded mode‐directed tabling in Prolog

Table space designs for implicit and explicit concurrent tabled evaluation

On the Implementation of a Cloud-Based Computing Test Bench Environment for Prolog Systems

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