Geographical information systems are ideal candidates for the application of parallel programming techniques, mainly because they usually handle large data sets. To help us deal with complex calculations over such data sets, we investigated the performance constraints of a classic master–worker parallel paradigm over a message-passing communication model. To this end, we present a new approach that employs an external database in order to improve the calculation–communication overlap, thus reducing the idle times for the worker processes. The presented approach is implemented as part of a parallel radio-coverage prediction tool for the Geographic Resources Analysis Support System GRASS environment. The prediction calculation employs digital elevation models and land-usage data in order to analyze the radio coverage of a geographical area. We provide an extended analysis of the experimental results, which are based on real data from an Long Term Evolution LTE network currently deployed in Slovenia. Based on the results of the experiments, which were performed on a computer cluster, the new approach exhibits better scalability than the traditional master–worker approach. We successfully tackled real-world-sized data sets, while greatly reducing the processing time and saturating the hardware utilization.
The task-parallelization problem within the GRASS environment has been addressed by several authors in a variety of studies. For example, in @cite_7 , the authors present a collection of GRASS modules for a watershed analysis. Their work concentrates on different ways of slicing raster maps to take advantage of a Message Passing Interface (MPI) implementation.
@cite_7
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This work proposes a joint implementation of spatially distributed runoff and soil erosion analysis in watersheds allowing subsequent modelization of nutrients transport processes originating from distributed sources. Implemented relying on the open source GRASS (Geographic Resources Analysis Support System) GIS (Geographical Information System), a new design for the raster operation routines is specially created to take advantage of the MPI possibilities and available GRID resources.