Subheap-Augmented Garbage Collection

Automated memory management avoids the tedium and danger of manual techniques. However, as no programmer input is required, no widely available interface exists to permit principled control over sometimes unacceptable performance costs. This dissertation explores the idea that performance-oriented languages should give programmers greater control over where and when the garbage collector (GC) expends effort. We describe an interface and implementation to expose heap partitioning and collection decisions without compromising type safety. We show that our interface allows the programmer to encode a form of reference counting using Hayes\u27 notion of key objects. Preliminary experimental data suggests that our proposed mechanism can avoid high overheads suffered by tracing collectors in some scenarios, especially with tight heaps. However, for other applications, the costs of applying subheaps---in human effort and runtime overheads---remain daunting

Garbage Collection Algorithms

This thesis focuses on an implementation of automatic memory management in C programming language. Mark-sweep method was modified for use in uncooperative programming language, which does not share data type information of memory slots accessible by the mutator. Due to this fact, decisions on pointer identity are conservative which guarantees safe collector operation - if value looks sufficiently like a pointer, it is considered a pointer (although it might not actually be one). Mark bits were moved from object's headers to bitmaps, stored in a seperate part of memory to prevent accidental writes to user's data by the collector. Finally, the usage of garbage collector was evaluated in practice

Garbage Collection Algorithms

This thesis focuses on an implementation of automatic memory management in C programming language. Mark-sweep method was modified for use in uncooperative programming language, which does not share data type information of memory slots accessible by the mutator. Due to this fact, decisions on pointer identity are conservative which guarantees safe collector operation - if value looks sufficiently like a pointer, it is considered a pointer (although it might not actually be one). Mark bits were moved from object's headers to bitmaps, stored in a seperate part of memory to prevent accidental writes to user's data by the collector. Finally, the usage of garbage collector was evaluated in practice

Analysing the Role of Memory in Oral History with respect to Urvashi Butalia’s The Other Side of Silence

Partition historiography of India based on oral narratives has tried to break the silence of affirmation created by the History of India. By adding plurality to the voices of the narrator, Urvashi Butalia through her book The Other Side of Silence (1998) shatters the authoritarian voice of a single historian. Memory of the survivors and the witnesses of the ‘great’ partition of 1947 is used as the sole defense to prove that history is a dialogue between the past and the progressively emerging future. Butalia’s work of non-fiction is therefore an account of the experiences narrated orally by survivors, who are now caught between the two national identities- one created by the memories they cherish before partition and the other stamped on them after the trauma of partition. The essay aims to present the challenges faced by this oral account of history, narrated through the faculty of individual memories with all its fallacies. It therefore eliminates the elevated status enjoyed by History as a branch of literature. It further discusses in detail the reliability of memory as a source of information. Ironically, the essay also helps to prove that historiography is just another method of storytelling embedding within itself opinions, individual interests and preferences

Do You Know What I Know?:Situational Awareness of Co-located Teams in Multidisplay Environments

Modern collaborative environments often provide an overwhelming amount of visual information on multiple displays. In complex project settings, the amount of visual information on multiple displays, and the multitude of personal and shared interaction devices in these environments can reduce the awareness of team members on ongoing activities, the understanding of shared visualisations, and the awareness of who is in control of shared artifacts. Research reported in this thesis addresses the situational awareness (SA) support of co-located teams working on team projects in multidisplay environments. Situational awareness becomes even more critical when the content of multiple displays changes rapidly, and when these provide large amounts of information. This work aims at getting insights into design and evaluation of shared display visualisations that afford situational awareness and group decision making. This thesis reports the results of three empirical user studies in three different domains: life science experimentation, decision making in brainstorming teams, and agile software development. The first and the second user studies evaluate the impact of the Highlighting-on-Demand and the Chain-of-Thoughts SA on the group decision-making and awareness. The third user study presents the design and evaluation of a shared awareness display for software teams. Providing supportive visualisations on a shared large display, we aimed at reducing the distraction from the primary task, enhancing the group decision-making process and the perceived task performance

Mapping the unseen: making sense of the subjective image.

It used to be thought that photography, as a kind of automatic mapping, could provide an objective view of the world. Now we are aware of the power of framing and other interventions between what is 'out there' and what is captured in depiction. Perhaps even perception, let alone depiction, shares this subjectivity? The Sapir-Whorf hypothesis holds that different cultures actually see the world in different ways, as evidenced and influenced by concepts in their languages – though this idea has been derided, for example by Pinker. A key difficulty is that the word subjectivity is bandied about without care for its different meanings and without distinguishing the many forms it takes in the graphic image. If into this muddle we introduce the idea of interactivity, still greater confusion easily follows. The chapter brings some order to different kinds and levels of subjectivity by documenting how they are reflected in forms of graphical mapping. In the process, it becomes clear how significant is the change in media technologies from those bound by the conventional rectangles of the page and screen to media which are interactive, pervasive, multimodal, physical and social

Back to (con)textuality: using chat services to teach legal reasoning

This paper discusses the technology-enhanced learning (TEL) environment named indicatively the 'Virtual Court', a text-based learning platform designed to introduce law students to the general dynamics of legal reasoning, particularly the argumentative character and open texture of the law. In the first two parts of the paper we reflect on the theoretical background behind the TEL, its earlier implementation and the lessons for the future drawn from that experience. In the third part, we propose developing the Virtual Court TEL environment into a cross-platform software application (app) that could be utilised within any programme and course for teaching law

Using Class-Level Static Properties to Predict Object Lifetimes

Today, most modern programming languages such as C # or Java use an automatic memory management system also known as a Garbage Collector (GC). Over the course of program execution, new objects are allocated in memory, and some older objects become unreachable (die). In order for the program to keep running, it becomes necessary to free the memory of dead objects; this task is performed periodically by the GC. Research has shown that most objects die young and as a result, generational collectors have become very popular over the years. Yet, these algorithms are not good at handling long-lived objects. Typically, long-lived objects would first be allocated in the nursery space and be promoted (copied) to an older generation after surviving a garbage collection, hence wasting precious time. By allocating long-lived and immortal objects directly into infrequently or never collected regions, pretenuring can reduce garbage collection costs significantly. Current state of the art methodology to predict object lifetime involves off-line profiling combined with a simple, heuristic classification. Profiling is slow (can take days), requires gathering gigabytes of data that need to be analysed (can take hours), and needs to be repeated for every previously unseen program. This thesis explores the space of lifetime predictions and shows how object lifetimes can be predicted accurately and quickly using simple program characteristics gathered within minutes. Following an innovative methodology introduced in this thesis, object lifetime predictions are fed into a specifically modified Java virtual machine. Performance tests show gains in GC times of as much as 77% for the “SPEC jvm98” benchmarks, against a generational copying collector