PathFence: Reducing Cross-Path Dependencies in Microservices

Maintaining low and consistent response times is crucial for mission-critical, user-facing applications (e.g., e-commerce sites and social media platforms) that are built on microservices architectures. However, through extensive benchmarking of microservice applications in cloud environments, we find that response time stability in microservices applications is fragile, with delays ranging from milliseconds to seconds, even under moderate CPU utilization level (e.g., 60%). An important cause of this instability is cross-path dependency, where multiple execution paths, triggered by different user requests, share certain common component microservices. As a result, a slowdown in one execution path (e.g., due to a transient bottleneck) can propagate and degrade the performance of other execution paths that share the same microservices. To address this challenge, we propose PathFence, a novel approach that reduces the impact of cross-path dependencies in microservices applications by isolating workloads from different execution paths at shared microservices. By dynamically allocating software resources (e.g., thread and connection pools) with the awareness of execution path and optimizing concurrency level on shared microservices, PathFence significantly improves response time stability. Based on three real-world workload traces and three representative microservices benchmarks, we show that PathFence reduces the 99th percentile response time by up to 80% and decreases the number of dropped requests by over 90%.