Yarn Scheduler Load Simulator (SLS) SLS is a stress and performance harness for the Yarn Resource Manager Scheduler that exercises the scheduler implementation simulating the cluster size and the applications load without having to have a cluster nor applications. SLS runs a regular RM without RPC endpoints and uses a NodeManager and Application Manager simulators to send and receive events simulating cluster and application load behavior. The size of the cluster and the application load is scripted in a configuration file.