Advances in Agent Oriented Software Engineering have focused on the provision of frameworks and toolkits to aid in the creation of Multi Agent Systems (MASs). However, despite the need to address the inherent complexity of such systems, little progress has been made in the development of tools to allow for the debugging and understanding of their inner workings. This paper introduces a novel performance analysis system, named AgentSpotter, which facilitates such analysis. AgentSpotter was developed by mapping conventional profiling concepts to the domain of MASs. We outline its integration into the Agent Factory multi agent framework.
Unique amongst all of the mainstream MAS development platforms, Cougaar is alone in integrating a performance measurement infrastructure directly into the system architecture @cite_4 . Although this is not applicable to other platforms, it does provide a good insight into the features that MAS developers could reasonably expect from any performance measurement application. The principal characteristics of this structure are as follows: Primary data channels consist of raw polling sensors at the heart of the system execution engine that gather simple low-impact data elements such as counters and event sensors. Secondary channels provide more elaborate information, such as summaries of the state of individual components and history analysis that stores performance data over lengthy running times. Computer-level metrics provide data on such items as CPU load, network load and memory usage. The message transport service gathers data on messages flowing through it. An extension mechanism based on servlets allows the addition of visualisation plugins that bind to the performance metrics data source. The service that is charged with gathering these metrics is designed so as to have no impact on system performance when not in use.
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A complex and vast amount of data will be collected from on-board sensors of operational connected vehicles (CVs), infrastructure data sources such as roadway sensors and traffic signals, mobile data sources such as cell phones, social media sources such as Twitter, and news and weather data services. Unfortunately, these data will create a bottleneck at data centers for processing and retrievals of collected data, and will require the deployment of additional message transfer infrastructure between data producers and consumers to support diverse CV applications. In this paper, we present a strategy for creating an efficient and low-latency distributed message delivery system for CV applications using a distributed message delivery platform. This strategy enables large-scale ingestion, curation, and transformation of unstructured data (roadway traffic-related and roadway non-traffic-related data) into labeled and customized topics for a large number of subscribers or consumers, such as CVs, mobile devices, and data centers. We evaluate the performance of this strategy by developing a prototype infrastructure using Apache Kafka, an open source message delivery system, and compared its performance with the latency requirements of CV applications. We present experimental results of the message delivery infrastructure on two different distributed computing testbeds at Clemson University: the Holocron cluster and the Palmetto cluster. Experiments were performed to measure the latency of the message delivery system for a variety of testing scenarios. These experiments reveal that measured latencies are less than the U.S. Department of Transportation recommended latency requirements for CV applications, which prove the efficacy of the system for CV related data distribution and management tasks. We investigate a wireless system of multiple cells, each having a downlink shared channel in support of high-speed packet data services. In practice, such a system consists of hierarchically organized entities including a central server, Base Stations (BSs), and Mobile Stations (MSs). Our goal is to improve global resource utilization and reduce regional congestion given asymmetric arrivals and departures of mobile users, a goal requiring load balancing among multiple cells. For this purpose, we propose a scalable cross-layer framework to coordinate packet-level scheduling, call-level cell-site selection and handoff, and system-level cell coverage based on load, throughput, and channel measurements. In this framework, an opportunistic scheduling algorithm--the weighted Alpha-Rule--exploits the gain of multiuser diversity in each cell independently, trading aggregate (mean) down-link throughput for fairness and minimum rate guarantees among MSs. Each MS adapts to its channel dynamics and the load fluctuations in neighboring cells, in accordance with MSs' mobility or their arrival and departure, by initiating load-aware handoff and cell-site selection. The central server adjusts schedulers of all cells to coordinate their coverage by prompting cell breathing or distributed MS handoffs. Across the whole system, BSs and MSs constantly monitor their load, throughput, or channel quality in order to facilitate the overall system coordination. Our specific contributions in such a framework are highlighted by the minimum-rate guaranteed weighted Alpha-Rule scheduling, the load-aware MS handoff cell-site selection, and the Media Access Control (MAC)-layer cell breathing. Our evaluations show that the proposed framework can improve global resource utilization and load balancing, resulting in a smaller blocking rate of MS arrivals without extra resources while the aggregate throughput remains roughly the same or improved at the hot-spots. Our simulation tests also show that the coordinated system is robust to dynamic load fluctuations and is scalable to both the system dimension and the size of MS population. By stacking layers of convolution and nonlinearity, convolutional networks (ConvNets) effectively learn from lowlevel to high-level features and discriminative representations. Since the end goal of large-scale recognition is to delineate complex boundaries of thousands of classes, adequate exploration of feature distributions is important for realizing full potentials of ConvNets. However, state-of-theart works concentrate only on deeper or wider architecture design, while rarely exploring feature statistics higher than first-order. We take a step towards addressing this problem. Our method consists in covariance pooling, instead of the most commonly used first-order pooling, of highlevel convolutional features. The main challenges involved are robust covariance estimation given a small sample of large-dimensional features and usage of the manifold structure of covariance matrices. To address these challenges, we present a Matrix Power Normalized Covariance (MPNCOV) method. We develop forward and backward propagation formulas regarding the nonlinear matrix functions such that MPN-COV can be trained end-to-end. In addition, we analyze both qualitatively and quantitatively its advantage over the well-known Log-Euclidean metric. On the ImageNet 2012 validation set, by combining MPN-COV we achieve over 4 , 3 and 2.5 gains for AlexNet, VGG-M and VGG-16, respectively; integration of MPN-COV into 50-layer ResNet outperforms ResNet-101 and is comparable to ResNet-152. The source code will be available on the project page: http: www.peihuali.org MPN-COV. Most software profiling tools quantify average performance and rely on a program's control flow graph to organize and report results. However, in interactive server applications, performance predictability is often an equally important measure. Moreover, the end user is often concerned with the performance of a semantically defined interval of execution, such as a request or transaction, which may not directly map to any single function in the call graph, especially in high-performance applications that use asynchrony or event-based programming. It is difficult to distinguish functionality that lies on the critical path of a semantic interval from other activity (e.g., periodic logging or side operations) that may nevertheless appear prominent in a conventional profile. Existing profilers lack the ability to (i) aggregate results for a semantic interval and (ii) attribute its performance variance to individual functions. We propose a profiler called VProfiler that, given the source code of a software system and programmer annotations indicating the start and end of semantic intervals of interest, is able to identify the dominant sources of latency variance in a semantic context. Using a novel abstraction, called a variance tree, VProfiler analyzes the thread interleaving and deconstructs overall latency variance into variances and covariances of the execution time of individual functions. It then aggregates latency variance along a backwards path of dependence relationships among threads from the end of an interval to its start. We evaluate VProfiler's effectiveness on three popular open-source projects (MySQL, Postgres, and Apache Web Server). By identifying a few culprit functions in these complex code bases, VProfiler allows us to eliminate 27 --82 of the overall latency variance of these systems with a modest programming effort.