This document summarizes Spark as a service on YARN clusters and discusses key features: - Spark on YARN allows running multiple workflows like Spark and Hadoop on the same cluster and improves resource utilization. The application master can dynamically request more containers as needed. - Qubole YARN clusters support autoscaling to upscale and downscale based on load and use spot instances for cost savings. - Spark applications were limited by initial resource allocation. Dynamic provisioning allows applications to request more executors or release unused executors to improve performance and cluster utilization.