Shared Resources

Shared resource effect

Another scaling effect that can jeopardize stability is the “shared resource” effect. Commonly seen in the guise of a service-oriented architecture or “common services” project, the shared resource is some facility that all members of a horizontally scalable layer need to use. With some application servers, the shared resource will be a cluster manager or a lock manager. When the shared resource gets overloaded, it’ll become a bottleneck limiting capacity. The following figure should give an idea of how the callers can put a hurting on the shared resource.