The economics of garbage collection

This paper argues that economic theory can improve our understanding of memory management. We introduce the allocation curve, as an analogue of the demand curve from microeconomics. An allocation curve for a program characterises how the amount of garbage collection activity required during its execution varies in relation to the heap size associated with that program. The standard treatment of microeconomic demand curves (shifts and elasticity) can be applied directly and intuitively to our new allocation curves. As an application of this new theory, we show how allocation elasticity can be used to control the heap growth rate for variable sized heaps in Jikes RVM

Efficient Management of Short-Lived Data

Motivated by the increasing prominence of loosely-coupled systems, such as mobile and sensor networks, which are characterised by intermittent connectivity and volatile data, we study the tagging of data with so-called expiration times. More specifically, when data are inserted into a database, they may be tagged with time values indicating when they expire, i.e., when they are regarded as stale or invalid and thus are no longer considered part of the database. In a number of applications, expiration times are known and can be assigned at insertion time. We present data structures and algorithms for online management of data tagged with expiration times. The algorithms are based on fully functional, persistent treaps, which are a combination of binary search trees with respect to a primary attribute and heaps with respect to a secondary attribute. The primary attribute implements primary keys, and the secondary attribute stores expiration times in a minimum heap, thus keeping a priority queue of tuples to expire. A detailed and comprehensive experimental study demonstrates the well-behavedness and scalability of the approach as well as its efficiency with respect to a number of competitors.Comment: switched to TimeCenter latex styl

Toxic Timescapes: Examining Toxicity across Time and Space

An interdisciplinary environmental humanities volume that explores human-environment relationships on our permanently polluted planet. While toxicity and pollution are ever present in modern daily life, politicians, juridical systems, media outlets, scholars, and the public alike show great difficulty in detecting, defining, monitoring, or generally coming to terms with them. This volume’s contributors argue that the source of this difficulty lies in the struggle to make sense of the intersecting temporal and spatial scales working on the human and more-than-human body, while continuing to acknowledge race, class, and gender in terms of global environmental justice and social inequality. The term toxic timescapes refers to this intricate intersectionality of time, space, and bodies in relation to toxic exposure. As a tool of analysis, it unpacks linear understandings of time and explores how harmful substances permeate temporal and physical space as both event and process. It equips scholars with new ways of creating data and conceptualizing the past, present, and future presence and possible effects of harmful substances and provides a theoretical framework for new environmental narratives. To think in terms of toxic timescapes is to radically shift our understanding of toxicants in the complex web of life. Toxicity, pollution, and modes of exposure are never static; therefore, dose, timing, velocity, mixture, frequency, and chronology matter as much as the geographic location and societal position of those exposed. Together, these factors create a specific toxic timescape that lies at the heart of each contributor’s narrative. Contributors from the disciplines of history, human geography, science and technology studies, philosophy, and political ecology come together to demonstrate the complex reality of a toxic existence. Their case studies span the globe as they observe the intersection of multiple times and spaces at such diverse locations as former battlefields in Vietnam, aging nuclear-weapon storage facilities in Greenland, waste deposits in southern Italy, chemical facilities along the Gulf of Mexico, and coral-breeding laboratories across the world.https://ohioopen.library.ohio.edu/oupress/1014/thumbnail.jp

Deterritorializing the Future

Understanding how pasts resource presents is a fundamental first step towards building alternative futures in the Anthropocene. This collection brings together scholars from a range of disciplines to explore concepts of care, vulnerability, time, extinction, loss and inheritance across more-than-human worlds, connecting contemporary developments in the posthumanities with the field of critical heritage studies. Drawing on contributions from archaeology, anthropology, critical heritage studies, gender studies, geography, histories of science, media studies, philosophy, and science and technology studies, the book aims to place concepts of heritage at the centre of discussions of the Anthropocene and its associated climate and extinction crises – not as a nostalgic longing for how things were, but as a means of expanding collective imaginations and thinking critically and speculatively about the future and its alternatives. Contributors: Christina Fredengren, Cecilia Åsberg, Anna Bohlin, Adrian Van Allen, Esther Breithoff, Rodney Harrison, Colin Sterling, Joanna Zylinska, Denis Byrne, J. Kelechi Ugwuanyi, Caitlin DeSilvey, Anatolijs Venovcevs, Anna Storm and Claire Colebrook

Deterritorializing the Future

Understanding how pasts resource presents is a fundamental first step towards building alternative futures in the Anthropocene. This collection brings together scholars from a range of disciplines to explore concepts of care, vulnerability, time, extinction, loss and inheritance across more-than-human worlds, connecting contemporary developments in the posthumanities with the field of critical heritage studies. Drawing on contributions from archaeology, anthropology, critical heritage studies, gender studies, geography, histories of science, media studies, philosophy, and science and technology studies, the book aims to place concepts of heritage at the centre of discussions of the Anthropocene and its associated climate and extinction crises – not as a nostalgic longing for how things were, but as a means of expanding collective imaginations and thinking critically and speculatively about the future and its alternatives. Contributors: Christina Fredengren, Cecilia Åsberg, Anna Bohlin, Adrian Van Allen, Esther Breithoff, Rodney Harrison, Colin Sterling, Joanna Zylinska, Denis Byrne, J. Kelechi Ugwuanyi, Caitlin DeSilvey, Anatolijs Venovcevs, Anna Storm and Claire Colebrook

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

The design and construction of high performance garbage collectors

Garbage collection is a performance-critical component of modern language implementations. The performance of a garbage collector depends in part on major algorithmic decisions, but also significantly on implementation details and techniques which are often incidental in the literature. In this dissertation I look in detail at the performance characteristics of garbage collection on modern architectures. My thesis is that a thorough understanding of the characteristics of the heap to be collected, coupled with measured performance of various design alternatives on a range of modern architectures provides insights that can be used to improve the performance of any garbage collection algorithm. The key contributions of this work are: 1) A new analysis technique (replay collection) for measuring the performance of garbage collection algorithms; 2) a novel technique for applying software prefetch to non-moving garbage collectors that achieves significant performance gains; and 3) a comprehensive analysis of object scanning techniques, cataloguing and comparing the performance of the known methods, and leading to a new technique that optimizes performance without significant cost to the runtime environment. These contributions are applicable to a wide range of garbage collectors, and can provide significant measurable speedups to a design point where each implementer in the past has had to trust intuition or their own benchmarking. The methodologies and implementation techniques contributed in this dissertation have the potential to make a significant improvement to the performance of every garbage collector

American Cities in Post- Apocalyptic Science Fiction

Visions of the American city in post-apocalyptic ruin permeate literary and popular fiction, across print, visual, audio and digital media. American Cities in Post-Apocalyptic Science Fiction explores the prevalence of these representations in American culture, drawing from a wide range of primary and critical works from the early-twentieth century to today. Beginning with science fiction in literary magazines, before taking in radio dramas, film, video games and expansive transmedia franchises, Robert Yeates argues that post-apocalyptic representations of the American city are uniquely suited for explorations of contemporary urban issues. Examining how the post-apocalyptic American city has been repeatedly adapted and repurposed to new and developing media over the last century, this book reveals that the content and form of such texts work together to create vivid and immersive fictional spaces in ways that would otherwise not be possible. Chapters present media-specific analyses of these texts, situating them within their historical contexts and the broader history of representations of urban ruins in American fiction. Original in its scope and cross-media approach, American Cities in Post-Apocalyptic Science Fiction both illuminates little-studied texts and provides provocative new readings of familiar works such as Blade Runner and The Walking Dead, placing them within the larger historical context of imaginings of the American city in ruins

Radiation Sounds

Jessica A. Schwartz examines the seventy-five years of Marshallese music developed in response to the United States’ nuclear weapons testing on their homeland, showing how Marshallese singing practices make heard the harmful effects of US nuclear violence