Amazon EMR now supports running multiple EMR steps at the same time, the ability to cancel running steps, and AWS Step Functions. Running steps in parallel allows you to run more advanced workloads, increase cluster resource utilization, and reduce the amount of time taken to complete your workload. The number of steps allowed to run at once is configurable and can be set when a cluster is launched and at any time after the cluster has started. With the ability to cancel running steps, you now have more control over step execution, including the ability to forcefully cancel steps. Running steps in parallel is also supported with AWS Step Functions, allowing you to create and scale clusters, and orchestrate step execution using Step Functions workflows.
Source:: Amazon AWS