PDP: prolog distributed processor for independent AND/OR parallel execution of Prolog
Lourdes Araujo, José Jaime Ruz · International Conference on Logic Programming · 1994
PDP Prolog Distributed Pro cessorfor Indep endentANDnOR ParallelExecutionofPrologLourdes AraujoJose J RuzDptoInformatica y AutomaticaUniversidad Complutense de MadridMadrid Spainflurdes jjruzgdiaucmesAbstractPDP Prolog Distributed Pro cessor is a multisequential system for Indep endentANDnOR parallel execution of Prolog The system is comp osed ofa set of workers controlled hierarchically Eachwer op erates on its ownprivate memory and interpro cessor communication is p erformed only by thepassing of messages Indep endent ANDparallelism is exploited following aforkjoinscheme and ORparallelism is exploited following a multisequential approach Both kinds of parallelism are implemented using closed environments To exploit ORparallelism the parentworker entisreconstructed in a new worker byrecomputingthe initial goal without backtracking following thesuccess pathobtained from the parentworker PDPdeals with ORunderAND parallelism pro ducing the solutions of a set ofparallel goals in a distributed way that is creating a new task for each element of the cross pro duct This approach has the advantageofavoiding b othstoring partial solutions and synchronizing workers resulting in a largely increased p erformance PDP has b een implemented on a transputer networkand p erformance results show that PDP intro duces very little overhead intosequential programs and provides a high sp eedup for coarse grain parallelprogramsIntro ductionThere are a considerable numb er of approaches prop osed for the parallelexecution of Prolog dealing with ORparallelism Indep endentANDparallelism and recently combining ANDOR parallelism Since most of these approaches are implemented on systems withtotally or partially shared memorywe are interested in investigating thep ossibilitie s of a completely distributed mo del of pro cessing that eliminatesthe shared memory contentionSopp orted by the Prontic pro ject TICC