Submit Work to a Cluster
This section describes the methods for submitting work to an Amazon EMR cluster. You can submit work to a cluster by adding steps or by interactively submitting Hadoop jobs to the master node. The maximum number of PENDING and ACTIVE steps allowed in a cluster is 256. You can submit jobs interactively to the master node even if you have 256 active steps running on the cluster. You can submit an unlimited number of steps over the lifetime of a long-running cluster, but only 256 steps can be ACTIVE or PENDING at any given time.
For clusters created using AMI version 3.1.0 and earlier (Hadoop 2.x) or AMI version 2.4.7 and earlier (Hadoop 1.x), the total number of steps available over the lifetime of a cluster is limited to 256. For more information about how to overcome this limitation, see Add More than 256 Steps to a Cluster.