LIMES M/R: Parallelization of the LInk discovery framework for MEtric Spaces using the Map/Reduce paradigm

The World Wide Web is the most important information space in the world. With the change of the web during the last decade, today’sWeb 2.0 offers everybody the possibility to easily publish information on the web. For instance, everyone can have his own blog, write Wikipedia articles, publish photos on Flickr or post status messages via Twitter. All these services on the web offer users all around the world the opportunity to interchange information and interconnect themselves with other users. However, the information, as it is usually published today, does not offer enough semantics to be machine-processable. As an example, Wikipedia articles are created using the lightweight Wiki markup language and then published as HyperText Markup Language (HTML) files whose semantics can easily be captured by humans, but not machines

Manual and Automatic Translation From Sequential to Parallel Programming On Cloud Systems

Cloud computing has gradually evolved into an infrastructural tool for a variety of scientific research and computing applications. It has become a trend for many institutions and organizations to migrate their products from local servers to the cloud. One of the current challenges in cloud computing is running software efficiently on cloud platforms since many legacy codes cannot be executed in parallel in cloud contexts, which is a waste of the cloud’s computing power. To solve this problem, we have researched ways to translate code from sequential to parallel cloud computing using three categories of translation methods: manual, automatic, and semi-automatic. The performance of manual translation result is better than the other two types of translation’s. However, it is costly to manually redesign and convert current sequential codes into cloud codes. Thus, the automatic translation of sequential codes to parallel cloud applications is one approach that could be taken to resolve the problem of code migration to a cloud infrastructure. During this research, two automatic code translators, Java to MapReduce (J2M) and Java to Spark (J2S), are developed to translate code automatically from sequential Java to MapReduce and Spark applications. A semi-automatic translation method is proposed, which is the combination of manual and automatic translation and performs well on large amounts of data with small fragment sizes. This dissertation provides details about our sequential to parallel cloud code translation research in last four years. The experimental results not only indicate that translators can precisely translate a sequential Java program into parallel cloud applications but also show that it can speed up performance. We expect that an almost linear rate of speedup is possible when processing large datasets. However, some constraints still need to be overcome so more features can be implemented in future work. It is believed that our translators are the ideal models for code migration and will play an important role in the transition era of cloud computing

Parallel feature selection for distributed-memory clusters

Versión final aceptada de: https://doi.org/10.1016/j.ins.2019.01.050This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/ licenses/by-nc-nd/4.0/. This version of the article: González-Domínguez, J. et al. (2019) ‘Parallel feature selection for distributed-memory clusters’, has been accepted for publication in Information Sciences, 496, pp. 399–409. The Version of Record is available online at: https://doi.org/10.1016/j.ins.2019.01.050[Abstract]: Feature selection is nowadays an extremely important data mining stage in the field of machine learning due to the appearance of problems of high dimensionality. In the literature there are numerous feature selection methods, mRMR (minimum-Redundancy-Maximum-Relevance) being one of the most widely used. However, although it achieves good results in selecting relevant features, it is impractical for datasets with thousands of features. A possible solution to this limitation is the use of the fast-mRMR method, a greedy optimization of the mRMR algorithm that improves both scalability and efficiency. In this work we present fast-mRMR-MPI, a novel hybrid parallel implementation that uses MPI and OpenMP to accelerate feature selection on distributed-memory clusters. Our performance evaluation on two different systems using five representative input datasets shows that fast-mRMR-MPI is significantly faster than fast-mRMR while providing the same results. As an example, our tool needs less than one minute to select 200 features of a dataset with more than four million features and 16,000 samples on a cluster with 32 nodes (768 cores in total), while the sequential fast-mRMR required more than eight hours. Moreover, fast-mRMR-MPI distributes data so that it is able to exploit the memory available on different nodes of a cluster and then complete analyses that fail on a single node due to memory constraints. Our tool is publicly available at https://github.com/borjaf696/Fast-mRMR.This research has been partially funded by projects TIN2016-75845-P and TIN-2015-65069-C2-1-R of the Ministry of Economy, Industry and Competitiveness of Spain, as well as by Xunta de Galicia projects ED431D R2016/045 and GRC2014/035, all of them partially funded by FEDER funds of the European Union. We gratefully thank CESGA for providing access to the Finis Terrae II supercomputer.Xunta de Galicia; ED431D R2016/045Xunta de Galicia; GRC2014/03

CoreTSAR: Task Scheduling for Accelerator-aware Runtimes

Heterogeneous supercomputers that incorporate computational accelerators such as GPUs are increasingly popular due to their high peak performance, energy efficiency and comparatively low cost. Unfortunately, the programming models and frameworks designed to extract performance from all computational units still lack the flexibility of their CPU-only counterparts. Accelerated OpenMP improves this situation by supporting natural migration of OpenMP code from CPUs to a GPU. However, these implementations currently lose one of OpenMP’s best features, its flexibility: typical OpenMP applications can run on any number of CPUs. GPU implementations do not transparently employ multiple GPUs on a node or a mix of GPUs and CPUs. To address these shortcomings, we present CoreTSAR, our runtime library for dynamically scheduling tasks across heterogeneous resources, and propose straightforward extensions that incorporate this functionality into Accelerated OpenMP. We show that our approach can provide nearly linear speedup to four GPUs over only using CPUs or one GPU while increasing the overall flexibility of Accelerated OpenMP

Evaluation and Analysis of Distributed Graph-Parallel Processing Frameworks

A number of graph-parallel processing frameworks have been proposed to address the needs of processing complex and large-scale graph structured datasets in recent years. Although significant performance improvement made by those frameworks were reported, comparative advantages of each of these frameworks over the others have not been fully studied, which impedes the best utilization of those frameworks for a specific graph computing task and setting. In this work, we conducted a comparison study on parallel processing systems for large-scale graph computations in a systematic manner, aiming to reveal the characteristics of those systems in performing common graph algorithms with real-world datasets on the same ground. We selected three popular graph-parallel processing frameworks (Giraph, GPS and GraphLab) for the study and also include a representative general data-parallel computing system— Spark—in the comparison in order to understand how well a general data-parallel system can run graph problems. We applied basic performance metrics measuring speed, resource utilization, and scalability to answer a basic question of which graph-parallel processing platform is better suited for what applications and datasets. Three widely-used graph algorithms— clustering coefficient, shortest path length, and PageRank score—were used for benchmarking on the targeted computing systems.We ran those algorithms against three real world network datasets with diverse characteristics and scales on a research cluster and have obtained a number of interesting observations. For instance, all evaluated systems showed poor scalability (i.e., the runtime increases with more computing nodes) with small datasets likely due to communication overhead. Further, out of the evaluated graphparallel computing platforms, PowerGraph consistently exhibits better performance than others

Pervasive Parallel And Distributed Computing In A Liberal Arts College Curriculum

We present a model for incorporating parallel and distributed computing (PDC) throughout an undergraduate CS curriculum. Our curriculum is designed to introduce students early to parallel and distributed computing topics and to expose students to these topics repeatedly in the context of a wide variety of CS courses. The key to our approach is the development of a required intermediate-level course that serves as a introduction to computer systems and parallel computing. It serves as a requirement for every CS major and minor and is a prerequisite to upper-level courses that expand on parallel and distributed computing topics in different contexts. With the addition of this new course, we are able to easily make room in upper-level courses to add and expand parallel and distributed computing topics. The goal of our curricular design is to ensure that every graduating CS major has exposure to parallel and distributed computing, with both a breadth and depth of coverage. Our curriculum is particularly designed for the constraints of a small liberal arts college, however, much of its ideas and its design are applicable to any undergraduate CS curriculum