YARN (Yet Another Resource Negotiator)

YARN, or Yet Another Resource Negotiator, is the resource-management and scheduling layer in Apache Hadoop. It separates the job of managing cluster capacity from the job of processing data, allowing different distributed-computing frameworks to share the same pool of machines rather than requiring a dedicated cluster for each workload.

A central ResourceManager decides how cluster resources are allocated, while a NodeManager runs on each worker machine and reports available capacity. Each submitted application also uses an ApplicationMaster to negotiate resources and coordinate its tasks. Work is executed inside containers that reserve resources such as memory and CPU for a specific application.

This architecture matters in large data environments because many workloads may compete for the same infrastructure. YARN provides the scheduling layer that helps Hadoop-based clusters run multiple jobs predictably while keeping resource allocation separate from the logic of the data-processing application itself.