arXiv subjects

Lauritz Thamsen

Publications and source records attributed to Lauritz Thamsen.

77 records · Page 5Linked to original sources

arXiv2021

A Scalable and Dependable Data Analytics Platform for Water Infrastructure Monitoring

With weather becoming more extreme both in terms of longer dry periods and more severe rain events, municipal water networks are increasingly under pressure. The effects include damages to the pipes, flash floods on the streets and combined sewer overflows. Retrofitting underground infrastructure is very expensive, thus water infrastructure operators are increasingly looking to deploy IoT solutions that promise to alleviate the problems at a fraction of the cost. In this paper, we report on preliminary results from an ongoing joint research project, specifically on the design and evaluation of its data analytics platform. The overall system consists of energy-efficient sensor nodes that send their observations to a stream processing engine, which analyzes and enriches the data and transmits the results to a GIS-based frontend. As the proposed solution is designed to monitor large and critical infrastructures of cities, several non-functional requirements such as scalability, responsiveness and dependability are factored into the system architecture. We present a scalable stream processing platform and its integration with the other components, as well as the algorithms used for data processing. We discuss significant challenges and design decisions, introduce an efficient data enrichment procedure and present empirical results to validate the compliance with the target requirements. The entire code for deploying our platform and running the data enrichment jobs is made publicly available with this paper.

cs.DC↗

arXiv2021

Hugo: A Cluster Scheduler that Efficiently Learns to Select Complementary Data-Parallel Jobs

Distributed data processing systems like MapReduce, Spark, and Flink are popular tools for analysis of large datasets with cluster resources. Yet, users often overprovision resources for their data processing jobs, while the resource usage of these jobs also typically fluctuates considerably. Therefore, multiple jobs usually get scheduled onto the same shared resources to increase the resource utilization and throughput of clusters. However, job runtimes and the utilization of shared resources can vary significantly depending on the specific combinations of co-located jobs. This paper presents Hugo, a cluster scheduler that continuously learns how efficiently jobs share resources, considering metrics for the resource utilization and interference among co-located jobs. The scheduler combines offline grouping of jobs with online reinforcement learning to provide a scheduling mechanism that efficiently generalizes from specific monitored job combinations yet also adapts to changes in workloads. Our evaluation of a prototype shows that the approach can reduce the runtimes of exemplary Spark jobs on a YARN cluster by up to 12.5%, while resource utilization is increased and waiting times can be bounded.

cs.DC↗

arXiv2021

Chiron: Optimizing Fault Tolerance in QoS-aware Distributed Stream Processing Jobs

Fault tolerance is a property which needs deeper consideration when dealing with streaming jobs requiring high levels of availability and low-latency processing even in case of failures where Quality-of-Service constraints must be adhered to. Typically, systems achieve fault tolerance and the ability to recover automatically from partial failures by implementing Checkpoint and Rollback Recovery. However, this is an expensive operation which impacts negatively on the overall performance of the system and manually optimizing fault tolerance for specific jobs is a difficult and time consuming task. In this paper we introduce Chiron, an approach for automatically optimizing the frequency with which checkpoints are performed in streaming jobs. For any chosen job, parallel profiling runs are performed, each containing a variant of the configurations, with the resulting metrics used to model the impact of checkpoint-based fault tolerance on performance and availability. Understanding these relationships is key to minimizing performance objectives and meeting strict Quality-of-Service constraints. We implemented Chiron prototypically together with Apache Flink and demonstrate its usefulness experimentally.

cs.DC↗

arXiv2021

Towards a Staging Environment for the Internet of Things

Internet of Things (IoT) applications promise to make many aspects of our lives more efficient and adaptive through the use of distributed sensing and computing nodes. A central aspect of such applications is their complex communication behavior that is heavily influenced by the physical environment of the system. To continuously improve IoT applications, a staging environment is needed that can provide operating conditions representative of deployments in the actual production environments -- similar to what is common practice in cloud application development today. Towards such a staging environment, we present Marvis, a framework that orchestrates hybrid testbeds, co-simulated domain environments, and a central network simulation for testing distributed IoT applications. Our preliminary results include an open source prototype and a demonstration of a Vehicle-to-everything (V2X) communication scenario.

cs.DC↗

arXiv2020

Fingerprinting Analog IoT Sensors for Secret-Free Authentication

Especially in context of critical urban infrastructures, trust in IoT data is of utmost importance. While most technology stacks provide means for authentication and encryption of device-to-cloud traffic, there are currently no mechanisms to rule out physical tampering with an IoT device's sensors. Addressing this gap, we introduce a new method for extracting a hardware fingerprint of an IoT sensor which can be used for secret-free authentication. By comparing the fingerprint against reference measurements recorded prior to deployment, we can tell whether the sensing hardware connected to the IoT device has been changed by environmental effects or with malicious intent. Our approach exploits the characteristic behavior of analog circuits, which is revealed by applying a fixed-frequency alternating current to the sensor, while recording its output voltage. To demonstrate the general feasibility of our method, we apply it to four commercially available temperature sensors using laboratory equipment and evaluate the accuracy. The results indicate that with a sensible configuration of the two hyperparameters we can identify individual sensors with high probability, using only a few recordings from the target device.

cs.CR↗