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The Communication Complexity of OptimizationJun 13 2019We consider the communication complexity of a number of distributed optimization problems. We start with the problem of solving a linear system. Suppose there is a coordinator together with $s$ servers $P_1, \ldots, P_s$, the $i$-th of which holds a subset ... More
The Consensus Number of a Cryptocurrency (Extended Version)Jun 13 2019Many blockchain-based algorithms, such as Bitcoin, implement a decentralized asset transfer system, often referred to as a cryptocurrency. As stated in the original paper by Nakamoto, at the heart of these systems lies the problem of preventing double-spending; ... More
Blockchain Games: A SurveyJun 13 2019With the support of the blockchain systems, the cryptocurrency has changed the world of virtual assets. Digital games, especially those with massive multi-player scenarios, will be significantly impacted by this novel technology. However, there are insufficient ... More
Mir-BFT: High-Throughput BFT for BlockchainsJun 13 2019This paper presents Mir-BFT (or, simply, Mir), a robust asynchronous Byzantine fault-tolerant (BFT) total order broadcast protocol aimed at maximizing throughput on wide-area networks (WANs) with up to 100 nodes. This deployment setting is highly relevant ... More
Optimizing Redundancy Levels in Master-Worker Compute Clusters for Straggler MitigationJun 12 2019Runtime variability in computing systems causes some tasks to straggle and take much longer than expected to complete. These straggler tasks are known to significantly slowdown distributed computation. Job execution with speculative execution of redundant ... More
Collaborative Broadcast in O(log log n) RoundsJun 12 2019We consider the multihop broadcasting problem for $n$ nodes placed uniformly at random in a disk and investigate the number of hops required to transmit a signal from the central node to all other nodes under three communication models: Unit-Disk-Graph ... More
Handel: Practical Multi-Signature Aggregation for Large Byzantine CommitteesJun 12 2019We present Handel, a Byzantine fault tolerant aggregation protocol that allows for the quick aggregation of cryptographic signatures over a WAN. Handel has logarithmic time and polylogarithmic network complexity and needs minimal computing resources. ... More
Application-Level Differential Checkpointing for HPC Applications with Dynamic DatasetsJun 12 2019High-performance computing (HPC) requires resilience techniques such as checkpointing in order to tolerate failures in supercomputers. As the number of nodes and memory in supercomputers keeps on increasing, the size of checkpoint data also increases ... More
Checkpoint/restart approaches for a thread-based MPI runtimeJun 12 2019Fault-tolerance has always been an important topic when it comes to running massively parallel programs at scale. Statistically, hardware and software failures are expected to occur more often on systems gathering millions of computing units. Moreover, ... More
Temporally-Biased Sampling Schemes for Online Model ManagementJun 11 2019To maintain the accuracy of supervised learning models in the presence of evolving data streams, we provide temporally-biased sampling schemes that weight recent data most heavily, with inclusion probabilities for a given data item decaying over time ... More
Membership-based Manoeuvre Negotiation in Autonomous and Safety-critical Vehicular SystemsJun 11 2019A fault-tolerant negotiation-based intersection crossing protocol is presented. Rigorous analytic proofs are used for demonstrating the correctness and fault-tolerance properties. Experimental results validate the correctness proof via detailed computer ... More
ROOT I/O compression algorithms and their performance impact within Run 3Jun 11 2019The LHCs Run3 will push the envelope on data-intensive workflows and, since at the lowest level this data is managed using the ROOT software framework, preparations for managing this data are starting already. At the beginning of LHC Run 1, all ROOT data ... More
Anomaly Detection in High Performance Computers: A Vicinity PerspectiveJun 11 2019In response to the demand for higher computational power, the number of computing nodes in high performance computers (HPC) increases rapidly. Exascale HPC systems are expected to arrive by 2020. With drastic increase in the number of HPC system components, ... More
Optimizing Pipelined Computation and Communication for Latency-Constrained Edge LearningJun 11 2019Consider a device that is connected to an edge processor via a communication channel. The device holds local data that is to be offloaded to the edge processor so as to train a machine learning model, e.g., for regression or classification. Transmission ... More
Optimizing Pipelined Computation and Communication for Latency-Constrained Edge LearningJun 11 2019Jun 12 2019Consider a device that is connected to an edge processor via a communication channel. The device holds local data that is to be offloaded to the edge processor so as to train a machine learning model, e.g., for regression or classification. Transmission ... More
Quantum Random Numbers generated by the Cloud Superconducting Quantum ComputerJun 11 2019A cloud quantum computer is similar to a random number generator in that its physical mechanism is inaccessible to the users. In this respect, a cloud quantum computer is a black box. In both devices, the users decide the device condition from the output. ... More
Window Based BFT Blockchain ConsensusJun 11 2019There is surge of interest to the blockchain technology not only in the scientific community but in the business community as well. Proof of Work (PoW) and Byzantine Fault Tolerant (BFT) are the two main classes of consensus protocols that are used in ... More
On the performance of various parallel GMRES implementations on CPU and GPU clustersJun 10 2019As the need for computational power and efficiency rises, parallel systems become increasingly popular among various scientific fields. While multiple core-based architectures have been the center of attention for many years, the rapid development of ... More
Analysis of parallel I/O use on the UK national supercomputing service, ARCHER using Cray LASSi and EPCC SAFEJun 10 2019In this paper, we describe how we have used a combination of the LASSi tool (developed by Cray) and the SAFE software (developed by EPCC) to collect and analyse Lustre I/O performance data for all jobs running on the UK national supercomputing service, ... More
LASSi: Metric based I/O analytics for HPCJun 10 2019LASSi is a tool aimed at analyzing application usage and contention caused by use of shared resources (filesystem or network) in a HPC system. LASSi was initially developed to support the ARCHER system where there are large variations in application requirements ... More
FairLedger: A Fair Blockchain Protocol for Financial InstitutionsJun 10 2019Financial institutions are currently looking into technologies for permissioned blockchains. A major effort in this direction is Hyperledger, an open source project hosted by the Linux Foundation and backed by a consortium of over a hundred companies. ... More
A Distributed Event-Triggered Control Strategy for DC Microgrids Based on Publish-Subscribe Model Over Industrial Wireless Sensor NetworksJun 09 2019This paper presents a complete design, analysis, and performance evaluation of a novel distributed event-triggered control and estimation strategy for DC microgrids. The primary objective of this work is to efficiently stabilize the grid voltage, and ... More
Federated AI lets a team imagine together: Federated Learning of GANsJun 09 2019Envisioning a new imaginative idea together is a popular human need. Imagining together as a team can often lead to breakthrough ideas, but the collaboration effort can also be challenging, especially when the team members are separated by time and space. ... More
Optimal Task Offloading and Resource Allocation for Fog ComputingJun 09 2019We propose a novel multi-tier fog and cloud computing architecture that enables edge nodes to cooperate in sharing computing and radio resources so as to minimize the total energy consumption of mobile users subject to their delay requirements. We first ... More
Lightweight Parallel Foundations: a model-compliant communication layerJun 07 2019We present the Lightweight Parallel Foundations (LPF), an interoperable and model-compliant communication layer adhering to a strict performance model of parallel computations. LPF consists of twelve primitives, each with strict performance guarantees, ... More
Distributed Learning with Random FeaturesJun 07 2019Jun 10 2019Distributed learning and random projections are the most common techniques in large scale nonparametric statistical learning. In this paper, we study the generalization properties of kernel ridge regression using both distributed methods and random features. ... More
Chauffeuring a Crashed Robot from a DiskJun 07 2019Evacuation of robots from a disk has attained a lot of attention recently. We visit the problem from the perspective of fault-tolerance. We consider two robots trying to evacuate from a disk via a single hidden exit on the perimeter of the disk. The robots ... More
Mr and ProfessorJun 06 2019In this paper, the authors propose to increase the efficiency of blockchain mining by using a population-based approach. Blockchain relies on solving difficult mathematical problems as proof-of-work within a network before blocks are added to the chain. ... More
A Non-Asymptotic Analysis of Network Independence for Distributed Stochastic Gradient DescentJun 06 2019This paper is concerned with minimizing the average of $n$ cost functions over a network, in which agents may communicate and exchange information with their peers in the network. Specifically, we consider the setting where only noisy gradient information ... More
Quantum Distributed Algorithm for the All-Pairs Shortest Path Problem in the CONGEST-CLIQUE ModelJun 06 2019The All-Pairs Shortest Path problem (APSP) is one of the most central problems in distributed computation. In the CONGEST-CLIQUE model, in which $n$ nodes communicate with each other over a fully connected network by exchanging messages of $O(\log n)$ ... More
The Architectural Implications of Facebook's DNN-based Personalized RecommendationJun 06 2019The widespread application of deep learning has changed the landscape of computation in the data center. In particular, personalized recommendation for content ranking is now largely accomplished leveraging deep neural networks. However, despite the importance ... More
Qsparse-local-SGD: Distributed SGD with Quantization, Sparsification, and Local ComputationsJun 06 2019Communication bottleneck has been identified as a significant issue in distributed optimization of large-scale learning models. Recently, several approaches to mitigate this problem have been proposed, including different forms of gradient compression ... More
Distributed Weighted Matching via Randomized Composable CoresetsJun 05 2019Maximum weight matching is one of the most fundamental combinatorial optimization problems with a wide range of applications in data mining and bioinformatics. Developing distributed weighted matching algorithms is challenging due to the sequential nature ... More
pCAMP: Performance Comparison of Machine Learning Packages on the EdgesJun 05 2019Machine learning has changed the computing paradigm. Products today are built with machine intelligence as a central attribute, and consumers are beginning to expect near-human interaction with the appliances they use. However, much of the deep learning ... More
pCAMP: Performance Comparison of Machine Learning Packages on the EdgesJun 05 2019Jun 06 2019Machine learning has changed the computing paradigm. Products today are built with machine intelligence as a central attribute, and consumers are beginning to expect near-human interaction with the appliances they use. However, much of the deep learning ... More
OpenEI: An Open Framework for Edge IntelligenceJun 05 2019In the last five years, edge computing has attracted tremendous attention from industry and academia due to its promise to reduce latency, save bandwidth, improve availability, and protect data privacy to keep data secure. At the same time, we have witnessed ... More
Distributed Training with Heterogeneous Data: Bridging Median and Mean Based AlgorithmsJun 04 2019Recently, there is a growing interest in the study of median-based algorithms for distributed non-convex optimization. Two prominent such algorithms include signSGD with majority vote, an effective approach for communication reduction via 1-bit compression ... More
Distributed Training with Heterogeneous Data: Bridging Median- and Mean-Based AlgorithmsJun 04 2019Jun 06 2019Recently, there is a growing interest in the study of median-based algorithms for distributed non-convex optimization. Two prominent such algorithms include signSGD with majority vote, an effective approach for communication reduction via 1-bit compression ... More
Nemesyst: A Hybrid Parallelism Deep Learning-Based Framework Applied for Internet of Things Enabled Food Retailing Refrigeration SystemsJun 04 2019Deep Learning has attracted considerable attention across multiple application domains, including computer vision, signal processing and natural language processing. Although quite a few single node deep learning frameworks exist, such as tensorflow, ... More
Reconfigurable Atomic Transaction Commit (Extended Version)Jun 04 2019Modern data stores achieve scalability by partitioning data into shards and fault-tolerance by replicating each shard across several servers. A key component of such systems is a Transaction Certification Service (TCS), which atomically commits a transaction ... More
Performance Modelling of Deep Learning on Intel Many Integrated Core ArchitecturesJun 04 2019Many complex problems, such as natural language processing or visual object detection, are solved using deep learning. However, efficient training of complex deep convolutional neural networks for large data sets is computationally demanding and requires ... More
A Hybrid Cache Architecture for Meeting Per-Tenant Performance Goals in a Private CloudJun 04 2019The in-memory cache system is an important component in a cloud for the data access performance. As the tenants may have different performance goals for data access depending on the nature of their tasks, effectively managing the memory cache is a crucial ... More
Assessing Performance Implications of Deep Copy Operations via MicrobenchmarkingJun 03 2019Jun 11 2019As scientific frameworks become sophisticated, so do their data structures. Current data structures are no longer simple in design and they have been progressively complicated. The typical trend in designing data structures in scientific applications ... More
Assessing Performance Implications of Deep Copy Operations via MicrobenchmarkingJun 03 2019As scientific frameworks become sophisticated, so do their data structures. Current data structures are no longer simple in design and they have been progressively complicated. The typical trend in designing data structures in scientific applications ... More
Exploiting nested task-parallelism in the $\mathcal{H}-LU$ factorizationJun 03 2019We address the parallelization of the LU factorization of hierarchical matrices ($\mathcal{H}$-matrices) arising from boundary element methods. Our approach exploits task-parallelism via the OmpSs programming model and runtime, which discovers the data-flow ... More
Cache Contention on Multicore Systems: An Ontology-based ApproachJun 03 2019Multicore processors have proved to be the right choice for both desktop and server systems because it can support high performance with an acceptable budget expenditure. In this work, we have compared several works in cache contention and found that ... More
Proximity Neighbor Selection in Blockchain NetworksJun 03 2019Blockchains have attracted a great deal of attention as a technology for the distributed management of register information at multiple nodes without a centralized system. However, they possess the drawbacks of low transaction throughput and long approval ... More
Mutable Locks: Combining the Best of Spin and Sleep LocksJun 02 2019In this article we present Mutable Locks, a synchronization construct with the same execution semantic of traditional locks (such as spin locks or sleep locks), but with a self-tuned optimized trade off between responsiveness---in the access to a just ... More
On the Use of Randomness in Local Distributed Graph AlgorithmsJun 02 2019We attempt to better understand randomization in local distributed graph algorithms by exploring how randomness is used and what we can gain from it: - We first ask the question of how much randomness is needed to obtain efficient randomized algorithms. ... More
Blockchain for Internet of Things: A SurveyJun 01 2019Jun 06 2019Internet of Things (IoT) is reshaping the incumbent industry to smart industry featured with data-driven decision-making. However, intrinsic features of IoT result in a number of challenges such as decentralization, poor interoperability, privacy and ... More
Patterns for Blockchain MigrationJun 01 2019With the rapid evolution of technological, economic, and regulatory landscapes, contemporary Blockchian platforms are all but certain to undergo major changes. Therefore, applications that rely on them will eventually need to migrate the Blockchain to ... More
Probabilistic Top-k Dominating Query Monitoring over Multiple Uncertain IoT Data Streams in Edge Computing EnvironmentsJun 01 2019Extracting the valuable features and information in Big Data has become one of the important research issues in Data Science. In most Internet of Things (IoT) applications, the collected data are uncertain and imprecise due to sensor device variations ... More
Probabilistic QoS-aware Placement of VNF chains at the EdgeJun 01 2019Network Function Virtualisation and Software Defined Networking are innovating the way network services are provisioned, by introducing a level of flexibility that is key for coping with requirements of complex traffic patterns in modern networking systems, ... More
A Technique for Finding Optimal Program Launch Parameters Targeting Manycore AcceleratorsJun 01 2019In this paper, we present a new technique to dynamically determine the values of program parameters in order to optimize the performance of a multithreaded program P. To be precise, we describe a novel technique to statically build another program, say, ... More
On the Parallelization of Triangular Decomposition of Polynomial SystemsMay 31 2019We discuss the parallelization of algorithms for solving polynomial systems symbolically by way of triangular decomposition. Algorithms for solving polynomial systems combine low-level routines for performing arithmetic operations on polynomials and high-level ... More
PowerSGD: Practical Low-Rank Gradient Compression for Distributed OptimizationMay 31 2019We study gradient compression methods to alleviate the communication bottleneck in data-parallel distributed optimization. Despite the significant attention received, current compression schemes either do not scale well or fail to achieve the target test ... More
Collaborative Decoding of Polynomial Codes for Distributed ComputationMay 31 2019We show that polynomial codes (and some related codes) used for distributed matrix multiplication are interleaved Reed-Solomon codes and, hence, can be collaboratively decoded. We consider a fault tolerant setup where $t$ worker nodes return erroneous ... More
Tracking in Order to Recover: Recoverable Lock-Free Data StructuresMay 31 2019We present the \emph{tracking approach} for deriving \emph{recoverable} implementations of several widely-used concurrent data structures. Recoverability is appealing for emerging systems featuring byte-addressable \emph{non-volatile main memory} (\emph{NVRAM}), ... More
From Global Choreographies to Provably Correct and Efficient Distributed ImplementationsMay 31 2019We define a method to automatically synthesize provably-correct efficient distributed implementations from high-level global choreographies. A global choreography describes the execution and communication logic between a set of provided processes which ... More
Isolation-Aware Timing Analysis and Design Space Exploration for Predictable and Composable Many-Core SystemsMay 31 2019Composable many-core systems enable the independent development and analysis of applications which will be executed on a shared platform where the mix of concurrently executed applications may change dynamically at run time. For each individual application, ... More
ParPaRaw: Massively Parallel Parsing of Delimiter-Separated Raw DataMay 31 2019Parsing is essential for a wide range of use cases, such as stream processing, bulk loading, and in-situ querying of raw data. Yet, the compute-intense step often constitutes a major bottleneck in the data ingestion pipeline, since parsing of inputs that ... More
Efficient Multiway Hash Join on Reconfigurable HardwareMay 31 2019We propose the algorithms for performing multiway joins using a new type of coarse grain reconfigurable hardware accelerator~-- ``Plasticine''~-- that, compared with other accelerators, emphasizes high compute capability and high on-chip communication ... More
Fast Online "Next Best Offers" using Deep LearningMay 31 2019In this paper, we present iPrescribe, a scalable low-latency architecture for recommending 'next-best-offers' in an online setting. The paper presents the design of iPrescribe and compares its performance for implementations using different real-time ... More
Reducing Tail Latency via Safe and Simple DuplicationMay 30 2019Duplication can be a powerful strategy for overcoming stragglers in cloud services, but is often used conservatively because of the risk of overloading the system. We present duplicate-aware scheduling or DAS, which makes duplication safe and easy to ... More
INFaaS: Managed & Model-less Inference ServingMay 30 2019The number of applications relying on inference from machine learning models is already large and expected to keep growing. For instance, Facebook applications issue tens-of-trillions of inference queries per day with varying performance, accuracy, and ... More
Visualizing a Moving Target: A Design Study on Task Parallel Programs in the Presence of Evolving Data and ConcernsMay 30 2019Common pitfalls in visualization projects include lack of data availability and the domain users' needs and focus changing too rapidly for the design process to complete. While it is often prudent to avoid such projects, we argue it can be beneficial ... More
The Bloom ClockMay 30 2019May 31 2019The bloom clock is a space-efficient, probabilistic data structure designed to determine the partial order of events in highly distributed systems. The bloom clock, like the vector clock, can autonomously detect causality violations by comparing its logical ... More
Temporal Parallelization of Bayesian Filters and SmoothersMay 30 2019This paper presents algorithms for the temporal parallelization of Bayesian filters and smoothers. We define the elements and the operators to pose these problems as the solutions to all-prefix-sums operations for which efficient parallel scan-algorithms ... More
On condition numbers of symmetric and nonsymmetric domain decomposition methodsMay 30 2019Using oblique projections and angles between subspaces we write condition number estimates for abstract nonsymmetric domain decomposition methods. In particular, we design and estimate the condition number of restricted additive Schwarz methods. We also ... More
Towards automatically building starting models for full-waveform inversion using global optimization methods: A PSO approach via DEAP + DevitoMay 30 2019In this work, we illustrate an example of estimating the macro-model of velocities in the subsurface through the use of global optimization methods (GOMs). The optimization problem is solved using DEAP (Distributed Evolutionary Algorithms in Python) and ... More
MCompiler: A Synergistic Compilation FrameworkMay 29 2019This paper presents a meta-compilation framework, the MCompiler. The main idea is that different segments of a program can be compiled with different compilers/optimizers and combined into a single executable. The MCompiler can be used in a number of ... More
Read-Uncommitted Transactions for Smart Contract PerformanceMay 29 2019Smart contract transactions demonstrate issues of performance and correctness that application programmers must work around. Although the blockchain consensus mechanism approaches ACID compliance, use cases that rely on frequent state changes are impractical ... More
The Impact of RDMA on AgreementMay 29 2019Remote Direct Memory Access (RDMA) is becoming widely available in data centers. This technology allows a process to directly read and write the memory of a remote host, with a mechanism to control access permissions. In this paper, we study the fundamental ... More
Putting Strong Linearizability in Context: Preserving Hyperproperties in Programs that Use Concurrent ObjectsMay 28 2019It has been observed that linearizability, the prevalent consistency condition for implementing concurrent objects, does not preserve some probability distributions. A stronger condition, called strong linearizability has been proposed, but its study ... More
On Counting the Population SizeMay 28 2019We consider the problem of counting the population size in the population model. In this model, we are given a distributed system of $n$ identical agents which interact in pairs with the goal to solve a common task. In each time step, the two interacting ... More
On mixing eventual and strong consistency: Bayou revisitedMay 28 2019In this paper we study the properties of eventually consistent distributed systems that feature arbitrarily complex semantics and mix eventual and strong consistency. These systems execute requests in a highly-available, weakly-consistent fashion, but ... More
Energy Efficiency Features of the Intel Skylake-SP Processor and Their Impact on PerformanceMay 28 2019The overwhelming majority of High Performance Computing (HPC) systems and server infrastructure uses Intel x86 processors. This makes an architectural analysis of these processors relevant for a wide audience of administrators and performance engineers. ... More
Function-as-a-Service Benchmarking FrameworkMay 28 2019Cloud Service Providers deliver their products in form of 'as-a-Service', which are typically categorized by the level of abstraction. This approach hides the implementation details and shows only functionality to the user. However, the problem is that ... More
Clairvoyant State Machine ReplicationMay 28 2019We propose a new protocol for the generalized consensus problem in asynchronous systems subject to Byzantine server failures. The protocol solves the consensus problem in a setting in which information about conflict between transactions is available ... More
On the Complexity of Distributed Splitting ProblemsMay 28 2019One of the fundamental open problems in the area of distributed graph algorithms is the question of whether randomization is needed for efficient symmetry breaking. While there are fast, $\text{poly}\log n$-time randomized distributed algorithms for all ... More
Distributed Linear Model Clustering over Networks: A Tree-Based Fused-Lasso ADMM ApproachMay 28 2019In this work, we consider to improve the model estimation efficiency by aggregating the neighbors' information as well as identify the subgroup membership for each node in the network. A tree-based $l_1$ penalty is proposed to save the computation and ... More
Brick: Asynchronous State ChannelsMay 27 2019Off-chain (Layer 2) protocols are a promising solution to the scalability and privacy challenges of blockchain systems. In off-chain protocols, or so-called channels, the core idea is that state changes between two parties in consensus need not be transparently ... More
An Accelerated Decentralized Stochastic Proximal Algorithm for Finite SumsMay 27 2019Modern large-scale finite-sum optimization relies on two key aspects: distribution and stochastic updates. For smooth and strongly convex problems, existing decentralized algorithms are slower than modern accelerated variance-reduced stochastic algorithms ... More
An Open-Source Benchmark Suite for Cloud and IoT MicroservicesMay 27 2019Cloud services have recently started undergoing a major shift from monolithic applications, to graphs of hundreds of loosely-coupled microservices. Microservices fundamentally change a lot of assumptions current cloud systems are designed with, and present ... More
Communication-Efficient Distributed Blockwise Momentum SGD with Error-FeedbackMay 27 2019Communication overhead is a major bottleneck hampering the scalability of distributed machine learning systems. Recently, there has been a surge of interest in using gradient compression to improve the communication efficiency of distributed neural network ... More
Direct Acyclic Graph based Blockchain for Internet of Things: Performance and Security AnalysisMay 27 2019Direct Acyclic Graph (DAG) based blockchain and the corresponding consensus mechanism has been identified as a promising technology for Internet of Things (IoT). Compared with Proof-of-Work (PoW) and Proof-of-Stake (PoS) that have been widely used in ... More
On fast probabilistic consensus in the Byzantine settingMay 26 2019In this paper we discuss a leaderless protocol of low communicational complexity which allows a set of nodes to come to a consensus on a value of a bit. In addition, we assume that part of the nodes are Byzantine, i.e., they are controlled by an adversary ... More
Improved Distributed Approximations for Minimum-Weight Two-Edge-Connected Spanning SubgraphMay 26 2019Jun 03 2019The minimum-weight $2$-edge-connected spanning subgraph (2-ECSS) problem is a natural generalization of the well-studied minimum-weight spanning tree (MST) problem, and it has received considerable attention in the area of network design. The latter problem ... More
Improved Distributed Approximations for Minimum-Weight Two-Edge-Connected Spanning SubgraphMay 26 2019The minimum-weight $2$-edge-connected spanning subgraph (2-ECSS) problem is a natural generalization of the well-studied minimum-weight spanning tree (MST) problem, and it has received considerable attention in the area of network design. The latter problem ... More
On the parallels between Paxos and Raft, and how to port optimizationsMay 26 2019In recent years, Raft has overtaken Paxos as the consensus algorithm of choice. [53] While many have pointed out similarities between the two protocols, no one has formally mapped out their relationships. In this paper, we show how Raft and Paxos are ... More
Deterministic Distributed Dominating Set Approximation in the CONGEST ModelMay 26 2019We develop deterministic approximation algorithms for the minimum dominating set problem in the CONGEST model with an almost optimal approximation guarantee. For $\epsilon>1/{\text{{poly}}}\log \Delta$ we obtain two algorithms with approximation factor ... More
Designing for Emergent Security in Heterogeneous Human-Machine TeamsMay 25 2019This work seeks to design decisionmaking rules for autonomous agents to jointly influence and optimize the behavior of teamed human decisionmakers in the presence of an adversary. We study a situation in which computational jobs are scheduled on servers ... More
Compress-Store on Blockchain: A Decentralized Data Processing and Immutable Storage for Multimedia StreamingMay 24 2019Decentralization for data storage is a challenging problem for blockchain-based solutions as the blocksize plays the key role for scalability. In addition, specific requirements of multimedia data calls for various changes in the blockchain technology ... More
Tight Linear Convergence Rate of ADMM for Decentralized OptimizationMay 24 2019The present paper considers leveraging network topology information to improve the convergence rate of ADMM for decentralized optimization, where networked nodes work collaboratively to minimize the objective. Such problems can be solved efficiently using ... More
Leader Stochastic Gradient Descent for Distributed Training of Deep Learning ModelsMay 24 2019We consider distributed optimization under communication constraints for training deep learning models. We propose a new algorithm, whose parameter updates rely on two forces: a regular gradient step, and a corrective direction dictated by the currently ... More
Polystore++: Accelerated Polystore System for Heterogeneous WorkloadsMay 24 2019Modern real-time business analytic consist of heterogeneous workloads (e.g, database queries, graph processing, and machine learning). These analytic applications need programming environments that can capture all aspects of the constituent workloads ... More
Hardness of Distributed OptimizationMay 24 2019This paper studies lower bounds for fundamental optimization problems in the CONGEST model. We show that solving problems exactly in this model can be a hard task, by providing $\tilde{\Omega}(n^2)$ lower bounds for cornerstone problems, such as minimum ... More
Performance-Feedback Autoscaling with Budget Constraints for Cloud-based Workloads of WorkflowsMay 24 2019The growing popularity of workflows in the cloud domain promoted the development of sophisticated autoscaling policies that allow automatic allocation and deallocation of resources. However, many state-of-the-art autoscaling policies for workflows are ... More
A Single SMC Sampler on MPI that Outperforms a Single MCMC SamplerMay 24 2019Markov Chain Monte Carlo (MCMC) is a well-established family of algorithms which are primarily used in Bayesian statistics to sample from a target distribution when direct sampling is challenging. Single instances of MCMC methods are widely considered ... More
winPIBT: Expanded Prioritized Algorithm for Iterative Multi-agent Path FindingMay 24 2019Providing agents with efficient paths so as not to collide with each other are called the Multi-agent Path Finding (MAPF) problem. Numerous solvers have been developed so far since MAPF is critical for practical applications such as automated warehouses. ... More