Statistical methods for locating performance problems in multi-tier applications

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 59-60).This thesis describes an algorithm developed to aid in solving the problem of performance diagnosis, by automatically identifying the specific component in a multicomponent application system responsible for a performance problem. The algorithm monitors the system, collecting load and latency information from each component, searches the data for patterns indicative of performance saturation using statistical methods, and uses a machine learning classifier to interpret those results. The algorithm was tested with two test applications in several configurations, with different performance problems synthetically introduced. The algorithm correctly located these problems as much as 90% of the time, indicating that this is a good approach to the problem of automatic performance problem location. Also, the experimentation demonstrated that the algorithm can locate performance problems in environments different from those for which it was designed and from that on which it was trained.by Michael R. Stunes.M.Eng

The Effects of Index Storage on Ranked Information Retrieval

Information retrieval is the process of recalling and ordering all relevant documents based on a user\u27s search query. Examples of information retrieval systems are Google, Bing, and Yahoo search. In order to perform an effective search, these systems utilize an inverted index for mapping content, such as words, to the original document. It is widely believed there are two options for implementing an inverted index and these options are in memory or as a file. This investigation looks at implementing an inverted index as a table in a database as compared to the other two options. In addition, this investigation will look at the optimal combination of inverted index implementation to retrieval algorithms such as TD-IDF, Best Match 25, and a unigram model with Jelinek-Mercer smoothing. This is determined by designing and developing a system which will index and search three different collections of various data, size, and complexities. By doing this, it is found that utilizing an inverted index implemented in a database is a viable option for information retrieval. It is also noteworthy that Best Match 25 or a unigram language model consistently outperforms TD-IDF. In conclusion, if the collection cannot be indexed in memory, then utilizing a database implemented index is a sufficient second option

How did Britain come to this? A century of systemic failures of governance

If every system is perfectly designed to get the results it gets, what is wrong with the design of the systems that govern Britain? And how have they resulted in failures in housing, privatisation, outsourcing, education and healthcare? In How Did Britain Come to This? Gwyn Bevan examines a century of varieties of systemic failures in the British state. The book begins and ends by showing how systems of governance explain scandals in NHS hospitals, and the failures and successes of the UK and Germany in responding to Covid-19 before and after vaccines became available. The book compares geographical fault lines and inequalities in Britain with those that have developed in other European countries and argues that the causes of Britain’s entrenched inequalities are consequences of shifts in systems of governance over the past century. Clement Attlee’s postwar government aimed to remedy the failings of the prewar minimal state, while Margaret Thatcher’s governments in the 1980s in turn sought to remedy the failings of Attlee’s planned state by developing the marketised state, which morphed into the financialised state we see today. This analysis highlights the urgent need for a new political settlement of an enabling state that tackles current systemic weaknesses from market failures and over-centralisation. This book offers an accessible, analytic account of government failures of the past century, and is essential reading for anyone who wants to make an informed contribution to what an innovative, capable state might look like in a post-pandemic world

Going national: nonprofit growth through geographic expansion

Thesis (Ed.D.)--Boston UniversityPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at [email protected]. Thank you.This research focused on understanding the process of nonprofit growth through geographic expansion, including challenges, opportunities, and critical decision points. A qualitative case study design was used. City Year and Citizen Schools, two Boston based, youth-serving organizations, served as the subjects of this study. Data collection included interviews with founders/leaders, board members, staff members, and other key informants; observation; and a review of internal and external documents. Using the principles of grounded theory, a Preliminary Nonprofit Geographic Expansion Model was developed through analysis of the two cases. Several major themes that emerged from the analysis were explored. This discussion of themes led to a Revised Nonprofit Geographic Expansion Model. Further study is required to test the generalizability of the Revised Nonprofit Expansion Model and relevant insights.2031-01-0

Accessibility Denied

This book explores the societal resistance to accessibility for persons with disabilities, and tries to set an example of how to study exclusion in a time when numerous policies promise inclusion. With 12 chapters organised in three parts, the book takes a comprehensive approach to accessibility, covering transport and communication, knowledge and education, law and organisation. Topics within a wide cross-disciplinary field are covered, including disability studies, social work, sociology, ethnology, social anthropology, and history. The main example is Sweden, with its implementation of the United Nations Convention on the Rights of Persons with Disabilities within the context of the Nordic welfare state. By identifying and discussing persistent social and cultural conditions as well as recurring situations and interactions that nurture resistance to advancing accessibility, despite various strong laws promoting it, the book’s conclusions are widely transferable. It argues for the value of alternating between methods, theoretical perspectives, and datasets to explore how new arenas, resources and technologies cause new accessibility concerns — and possibilities — for persons living with impairments. We need to be able to follow actors closely to uncover how they feel, act, and argue, but also to connect to wider discursive and institutional patterns and systems. This book will be of interest to scholars and students of disability studies, social work, sociology, ethnology, social anthropology, political science, and organisation studies

Quantifying Performance Costs of Database Fine-Grained Access Control

Fine-grained access control is a conceptual approach to addressing database security requirements. In relational database management systems, fine-grained access control refers to access restrictions enforced at the row, column, or cell level. While a number of commercial implementations of database fine-grained access control are available, there are presently no generalized approaches to implementing fine-grained access control for relational database management systems. Fine-grained access control is potentially a good solution for database professionals and system architects charged with designing database applications that implement granular security or privacy protection features. However, in the oral tradition of the database community, fine-grained access control is spoken of as imposing significant performance penalties, and is therefore best avoided. Regardless, there are current and emerging social, legal, and economic forces that mandate the need for efficient fine-grained access control in relational database management systems. In the study undertaken, the author was able to quantify the performance costs associated with four common implementations of fine-grained access control for relational database management systems. Security benchmarking was employed as the methodology to quantify performance costs. Synthetic data from the TPC-W benchmark as well as representative data from a real-world application were utilized in the benchmarking process. A simple graph-base performance model for Fine-grained Access Control Evaluation (FACE) was developed from benchmark data collected during the study. The FACE model is intended for use in predicting throughput and response times for relational database management systems that implement fine-grained access control using one of the common fine-grained access control mechanisms - authorization views, the Hippocratic Database, label-based access control, and transparent query rewrite. The author also addresses the issue of scalability for fine-grained access control mechanisms that were evaluated in the study

Proxies: the cultural work of standing in

How those with the power to design technology, in the very moment of design, are allowed to imagine who is included—and who is excluded—in the future. The open access edition of this book was made possible by generous funding from Arcadia – a charitable fund of Lisbet Rausing and Peter Baldwin. Our world is built on an array of standards we are compelled to share. In Proxies, Dylan Mulvin examines how we arrive at those standards, asking, “To whom and to what do we delegate the power to stand in for the world?” Mulvin shows how those with the power to design technology, in the very moment of design, are allowed to imagine who is included—and who is excluded—in the future. For designers of technology, some bits of the world end up standing in for other bits, standards with which they build and calibrate. These “proxies” carry specific values, even as they disappear from view. Mulvin explores the ways technologies, standards, and infrastructures inescapably reflect the cultural milieus of their bureaucratic homes. Drawing on archival research, he investigates some of the basic building-blocks of our shared infrastructures. He tells the history of technology through the labor and communal practices of, among others, the people who clean kilograms to make the metric system run, the women who pose as test images, and the actors who embody disease and disability for medical students. Each case maps the ways standards and infrastructure rely on prototypical ideas of whiteness, able-bodiedness, and purity to control and contain the messiness of reality. Standards and infrastructures, Mulvin argues, shape and distort the possibilities of representation, the meaning of difference, and the levers of change and social justice