Execution Dependencies in Microservices

Figure 1. Blocking effects among different execution paths. Resource saturation in a single service can cascade across multiple execution paths, causing severe performance damage.

Microservice applications decompose monolithic business logic into loosely coupled microservices, introducing complex inter-service dependencies. This architectural shift poses a significant challenge to maintaining system-wide performance stability: resource contention in a single microservice can cascade, causing blocking effects cross different execution paths. As a result, performance degradation from transient bottlenecks in a microservice is not limited to its own execution path but instead propagates across multiple execution paths, leading wide-spread performance degradation.

Figure 2. Conceptual illustration of cross-service queue blocking.

Execution blocking occurs when resource saturation happens directly on a shared upstream microservice. In such a scenario, the shared upstream microservice becomes a bottleneck, blocking the execution of all dependent downstream microservices across different execution paths. However, cross-service queue blocking is more challenging to detect and mitigate because the resource saturation and the blocking effect occur on different microservices. In such a scenario, resource saturation can happen on any downstream microservice (DM) in one execution path and block the execution of other execution paths.