Scheduling divisible loads in heterogeneous distributed systems

Wydział Matematyki i Informatyki: Zakład Algorytmiki i ProgramowaniaCelem rozprawy jest analiza pewnych zagadnień szeregowania zadań jednorodnie podzielnych w heterogenicznych systemach rozproszonych i konstrukcja algorytmów rozwiązujących te problemy. Jako pierwszy rozważany był problem jednoetapowego szeregowania zadań jednorodnie podzielnych w topologii gwiazdy. Zaproponowano w pełni wielomianowe schematy aproksymacji i algorytmy aproksymacyjne dla tego problemu. Następnie rozważany był problem wieloetapowego szeregowania zadań jednorodnie podzielnych. Przeprowadzono analizę eksperymentalną własności problemu. Na podstawie otrzymanych wyników skonstruowano algorytmy heurystyczne. Zostały one ocenione i porównane eksperymentalnie. Teoria zadań jednorodnie podzielnych została także zastosowana do modelowania, analizy i szeregowania aplikacji MapReduce. Skonstruowano model matematyczny i algorytmy szeregowania takich obliczeń. Przeprowadzono ocenę efektywności MapReduce. Model został następnie uogólniony na aplikacje wielowarstwowe. Podano algorytmy szeregowania takich aplikacji i przeanalizowano wpływ parametrów systemu na strukturę uszeregowania.The main goal of this work is the analysis of several divisible load scheduling problems in heterogeneous distributed systems and the construction of algorithms solving these problems. First, single-round divisible load scheduling in star networks is analyzed. Fully polynomial time approximation schemes and approximation algorithms are proposed for this problem. Then, multi-round divisible load scheduling with memory limits is investigated. An extensive computational study of the features of the problem is provided. These results are used to construct heuristic algorithms solving the problem. The algorithms are evaluated and compared based on the experimental results. The divisible load theory is also applied to model, analyze and schedule computations in the MapReduce framework. A mathematical model of such computations is constructed and scheduling algorithms are proposed. Performance limits of the proposed organization of computations are investigated. Afterwards, the model is generalized to handle multilayer applications. Scheduling algorithms for multilayer applications are given and the influence of the system parameters on the schedule structure is studied

Scheduling Multilayer Divisible Computations

We analyze scheduling multilayer divisible computations. Multilayer computations consist of a chain of parallel applications, such that one application produces input for the next one. A simple form of multilayer computations are MapReduce parallel applications. The operations of mapping and reducing are two divisible applications with precedence constraints. We propose a divisible load model and give an algorithm for scheduling multilayer divisible computations. The algorithm is tested in a series of computational experiments. We draw conclusions on schedule patterns and determinants of the performance

LEARNING ENGLISH WHILE EXPLORING THE NATIONAL CULTURAL HERITAGE: TECHNOLOGY-ASSISTED PROJECT-BASED LANGUAGE LEARNING IN AN UPPER-SECONDARY SCHOOL

The quality and content of English language courses offered in secondary schools require special attention as they affect many students who learn English as one of their school subjects. Despite curricular provisions prescribing balanced development of language competence and a number of so-called “key competences”, class work in Polish upper-secondary schools heavily focuses on developing students’ selected language skills and language systems, i.e. the areas that are tested during school-exit exams, neglecting civic competences (i.e. group work) and digital skills. It is suggested that technology-assisted project-based language learning can help remedy this situation. Accordingly, the aim of this article is to outline a class project that illustrates the integration of project-based learning approach in language (English) and content (Polish language and culture) learning, the execution of which necessitates collaboration in groups, as well as the use of technology. It is hoped that the presented project will provide inspiration and guidance on how to engage upper-secondary school students in meaningful project work so that the development of target competences can be facilitated