Software aging is a phenomenon defined as the continuing degradation of software systems during runtime, being particularly noticeable in long-running applications. Memory-related aging effects are one of the most important problems in this research field. Therefore understanding their causes and how they work is a major requirement in designing dependable software systems. In this paper we go deep into how memory management works inside application process, focusing on two memory problems that cause software aging: fragmenting and leakage. We explain the mechanics of memory-related software aging effects dissecting a real and widely adopted memory allocator. Along with the theoretical explanation, we present an experimental study that illustrates how memory fragmenting and leakage occur and how they accumulate over time in order to cause system aging-related failures.
The learning experience in virtual environments can be significantly improved through the effective introduction of collaborative learning. The group formation of students is a crucial aspect in a such learning. Due to the lack of interaction between students, this task becomes complex, requiring automatic and intelligent tools to help students, tutors and environments to determine groupings for collaborative work. This article is a joint effort of two research groups, aimed at fostering the advancement of collaborative learning, presenting the use of personality traits of the Big Five model, identified through natural language texts produced by students. The experiments performed independently were compared, demonstrating the feasibility of the proposals.Resumo. A experiência de aprendizagem em ambientes virtuais pode ser significativamente melhorada através da introdução efetiva de aprendizagem colaborativa. A formação de gruposé um aspecto crucial para este tipo de aprendizagem. Devidoà ausência de interação entre estudantes, esta tarefa torna-se complexa, sendo necessárias ferramentas para auxiliar a determinar agrupamentos para trabalho colaborativo. Este artigoé um esforço conjunto de dois grupos de pesquisa, visando promover o avanço da aprendizagem colaborativa, utilizando o modelo Big Five de personalidade, identificados nos textos produzidos pelos alunos. Os experimentos realizados independentemente foram comparados, demonstrando a viabilidade das propostas.
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