The login nodes of the cluster, vortex1 and vortex2, have a 20 minute time limit on user processes to prevent users from consuming all the processing and memory on the login nodes. If you are trying to test a program, you can use the debug queue which has a time limit of 1 hour. You can launch an interactive job which will log you into a compute node and allow you to compile code, test your job, etc.
More details about using the debug queue can be found here:
More details about running interactive jobs can be found here: