Anomaly diagnosis relying on system logs to record runtime events is essential for improving the service quality of distributed systems and reducing economic losses. However, most existing log-based anomaly detection approaches depend on the assumption of the fixed quantitative or sequential patterns of a normal log event sequence. This assumption is challenged in the context of practical distributed and parallel systems due to the dynamic pattern of the log sequence, log data noise as well as concurrency of multiple anomalies. Against these challenges, this paper aims to perform the robust log-based anomaly diagnosis by capturing the event context information of the log event graph, called LogGraph, instead of straightforwardly employing the fixed quantitative or sequential patterns of the log records, thus reducing its sensitivity to the log flaws and the concurrency of multiple anomalies. Specifically, in order to handle multiple anomalies concurrency, LogGraph invokes the association rule to decouple log sequences. It further reinterprets a log record sequence into a log event graph modeled by event semantic embedding and event adjacency matrix. An attention-based Gated Graph Neural Network (GGNN) model is developed to capture the semantic information of the log graph, which enables the fine-grained and robust anomaly identification of the proposed scheme. We use real log data sets collected from Hadoop systems and network switches to verify the effectiveness of the proposed LogGraph in log data scenarios that contain noise and multiple anomalies concurrency problems. The experimental results show that the proposed LogGraph achieves high performance and strong robustness in anomaly diagnosis.

As a new computing paradigm, multi-data center computing enables service providers to deploy their applications close to the users. However, due to the spatio-temporal changes in workloads, it is challenging to coordinate multiple distributed data centers to provide high-quality services while reducing service operation costs. To address this challenge, this article studies the joint optimization problem of task scheduling and resource scaling in multi-data center systems. Since the task scheduling and the resource scaling are usually performed in different timescales, we decompose the joint optimization problem into two sub-problems and propose a two-timescale optimization framework. The short-timescale task scheduling can promptly relieve the bursty arrivals of computing tasks, and the long-timescale resource scaling can adapt well to the long-term changes in workloads. To address the distributed optimization problem, we propose a two-timescale multi-agent deep reinforcement learning algorithm. In order to characterize the graph-structured states of connected data centers, we develop a directed graph convolutional network based global state representation model. The evaluation indicates that the proposed algorithm is able to reduce both the task makespan and the task timeout while maintaining a reasonable cost.

Deploying microservices on the cooperative edge computing system greatly shortens the interaction delay between users and service and alleviates the traffic burden on the backbones, which has emerged as a new paradigm for service provision. However, it is challenging to embed microservices, having diverse resource demands and heterogeneous invocation relationships, into a distributed edge computing system with irregular network topology. In order to characterize the invocation relationship, we conceive a graph attention network based model to capture the structural features of microservices. Similarly, we propose a multi-channel directed graph convolutional network model to capture the spatial dynamic of edge resources distribution, which jointly considers the heterogeneity of the edge nodes and the links between them. Then, we develop a sequence-to-sequence based multi-step decision model, which maps the feature sequence of the current state to a sequence of deployment actions. Using this model, we further propose a microservice deployment algorithm based on graph neural network aided deep reinforcement learning, where a parallel asynchronous training process is used to accelerate convergence. The performance evaluation shows that the proposed algorithm can improve the deployment success ratio and resource utilization, while ensuring the load balance of edge nodes.