Overcoming extreme-scale reproducibility challenges through a unified, targeted, and multilevel toolset

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Overcoming extreme-scale reproducibility challenges through a unified, targeted, and multilevel toolset

pre-printReproducibility, the ability to repeat program executions with the same numerical result or code behavior, is crucial for computational science and engineering applications. However, non-determinism in concurrency scheduling often hampers achieving this ability on high performance computing (HPC) systems. To aid in managing the adverse effects of non-determinism, prior work has provided techniques to achieve bit-precise reproducibility, but most of them focus only on small-scale parallelism. While scalable techniques recently emerged, they are disparate and target special purposes, e.g., single-schedule domains. On current systems with O(106) compute cores and future ones with O(109), any technique that does not embrace a unied, targeted, and multilevel approach will fall short of providing reproducibility. In this paper, we argue for a common toolset that embodies this approach, where programmers select and compose complementary tools and can effectively, yet scalably, analyze, control, and eliminate sources of non-determinism at scale. This allows users to gain reproducibility only to the levels demanded by specific code development needs. We present our research agenda and ongoing work toward this goal

Overcoming Extreme-Scale Reproducibility Challenges Through a Unified, Targeted and Multilevel Toolset Overcoming Extreme-Scale Reproducibility Challenges Through a Unified, Targeted, and Multilevel Toolset *

ABSTRACT Reproducibility, the ability to repeat program executions with the same numerical result or code behavior, is crucial for computational science and engineering applications. However, non-determinism in concurrency scheduling often hampers achieving this ability on high performance computing (HPC) systems. To aid in managing the adverse effects of non-determinism, prior work has provided techniques to achieve bit-precise reproducibility, but most of them focus only on small-scale parallelism. While scalable techniques recently emerged, they are disparate and target special purposes, e.g., single-schedule domains. On current systems with O(10 6 ) compute cores and future ones with O(10 9 ), any technique that does not embrace a unified, targeted, and multilevel approach will fall short of providing reproducibility. In this paper, we argue for a common toolset that embodies this approach, where programmers select and compose complementary tools and can effectively, yet scalably, analyze, control, and eliminate sources of non-determinism at scale. This allows users to gain reproducibility only to the levels demanded by specific code development needs. We present our research agenda and ongoing work toward this goal

Supercomputing Frontiers

This open access book constitutes the refereed proceedings of the 6th Asian Supercomputing Conference, SCFA 2020, which was planned to be held in February 2020, but unfortunately, the physical conference was cancelled due to the COVID-19 pandemic. The 8 full papers presented in this book were carefully reviewed and selected from 22 submissions. They cover a range of topics including file systems, memory hierarchy, HPC cloud platform, container image configuration workflow, large-scale applications, and scheduling

LIPIcs, Volume 277, GIScience 2023, Complete Volume

LIPIcs, Volume 277, GIScience 2023, Complete Volum

Climate Change and Environmental Sustainability-Volume 1

Climate change has been widely recognised as a major challenge to the world, with significant environmental, economic and social consequences. Given this, addressing climate change is an urgent and profound task of society, a complex and difficult mission of several generations. To address the challenge of climate change, there is a need to develop a holistic climate change mitigation and adaptation framework that can cover as many climate-related topics as possible and connect as many stakeholders as possible across the globe. This book is an important one, bringing together key climate-related topics, including climate-induced impact assessment, environmental vulnerability and resilience assessment, greenhouse gas emission dynamics and sequestration, climate change mitigation and adaptation strategies in addition to climate-related governance. Results reported in this book are conducive to a better understanding of the climate emergency, climate-related impacts and the solutions. We expect the book to benefit decision makers, practitioners and researchers in different fields such as climate modelling and prediction, forest ecosystems, land management, urban planning and design, urban governance in addition to institutional operation. Prof. Bao-Jie He acknowledges Project NO. 2021CDJQY-004, supported by the Fundamental Research Funds for the Central Universities. We appreciate the assistance from Mr. Lifeng Xiong, Mr. Wei Wang, Ms. Xueke Chen and Ms. Anxian Chen at the School of Architecture and Urban Planning, Chongqing University, China

Smart Urban Water Networks

This book presents the paper form of the Special Issue (SI) on Smart Urban Water Networks. The number and topics of the papers in the SI confirm the growing interest of operators and researchers for the new paradigm of smart networks, as part of the more general smart city. The SI showed that digital information and communication technology (ICT), with the implementation of smart meters and other digital devices, can significantly improve the modelling and the management of urban water networks, contributing to a radical transformation of the traditional paradigm of water utilities. The paper collection in this SI includes different crucial topics such as the reliability, resilience, and performance of water networks, innovative demand management, and the novel challenge of real-time control and operation, along with their implications for cyber-security. The SI collected fourteen papers that provide a wide perspective of solutions, trends, and challenges in the contest of smart urban water networks. Some solutions have already been implemented in pilot sites (i.e., for water network partitioning, cyber-security, and water demand disaggregation and forecasting), while further investigations are required for other methods, e.g., the data-driven approaches for real time control. In all cases, a new deal between academia, industry, and governments must be embraced to start the new era of smart urban water systems

Considerations for the interdisciplinary development of environmental system models

Effective decision making and policy development requires holistic consideration of the modelling context. This thesis explores how consideration of multiple disciplinary perspectives and concerns lead to an integrative model development process for the purpose of socio-environmental systems (SES) management. The research is presented through two frames: (1) Integrated Environmental Model (IEM) development through a System-of-Systems (SoS) approach, and (2) the socio-technical considerations within an interdisciplinary modelling process. The presented research incorporates the perspectives of the modelling, systems engineering, and software development paradigms. IEMs are developed for the purpose of integrating knowledge across the various disciplines involved, whereas traditional approaches focus on single systems within the SES, such as hydrology, economics, social dynamics, or climatic drivers. Use of IEMs allows for the consideration of the flow-on effects due to system changes and interaction, and how these may affect long-term SES behaviour. Pathways that are robust - i.e., lead to beneficial or desirable outcomes - under a range of plausible but uncertain conditions can then be identified and assessed. An interconnected network of system models thus makes up an SoS model allowing consideration of higher-order effects. In practice, however, the decisions and approaches taken in developing constituent models may influence integrated system behaviour once coupled. The socio-technical modelling concerns within the SoS/SES modelling context, including the methods to assess and manage model validity, complexity, and uncertainty, with respect to model purpose and intended outcomes are explored through a series of publications. This thesis contributes to the growing body of knowledge through: 1. An expansive overview of the currently available software for model uncertainty and sensitivity analysis, and the techniques they encompass 2. An integrated environmental model for the Lower Campaspe catchment in North-Central Victoria, Australia. The model explores long-term implications of water management decisions and potential policy changes (primarily through an agricultural lens), including conjunctive use of surface and groundwater under a range of uncertain futures. 3. Demonstration of a property-based sensitivity analysis approach to model diagnostics that combines software testing and sensitivity analysis to validate model behaviour. The approach is useful as a first-pass screening tool. Failure to reproduce expected model behaviour indicates issues with the model to be corrected and avoids the necessity of more computationally demanding diagnostics. 4. A pragmatic step-by-step framework for the sensitivity analysis of spatially distributed environmental models 5. Exploration and discussion of the modelling practices, issues and challenges that arise when dealing with the various influences and effects of scale within the interdisciplinary SoS context through a socio-technical lens. The discussion leads to a call for a grander vision for SoS-IEM modelling (and commensurate funding) to better enable interdisciplinary, and integrative, socio-environmental research to occur. 6. A shared reflexive account of two case studies that draws out the considerations and decisions regarding scale to arrive at five shared lessons learnt to foster an effective interdisciplinary modelling process. The key conclusion is the need for researchers involved in SoS modelling of SESs to actively consider and address cross-disciplinary concerns through improved interdisciplinary communication, documentation practices, and explicit consideration of the interplay between defined scales and resulting influence on uncertainty. Integrative consideration of these would then lower or avoid barriers that hamper the development and application of integrated environmental system models

Fundamental Approaches to Software Engineering

This open access book constitutes the proceedings of the 23rd International Conference on Fundamental Approaches to Software Engineering, FASE 2020, which took place in Dublin, Ireland, in April 2020, and was held as Part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2020. The 23 full papers, 1 tool paper and 6 testing competition papers presented in this volume were carefully reviewed and selected from 81 submissions. The papers cover topics such as requirements engineering, software architectures, specification, software quality, validation, verification of functional and non-functional properties, model-driven development and model transformation, software processes, security and software evolution