How to efficiently utilize all cores?

Hi, I have a cluster setup with three slaves, 4 cores each(12 cores in total). When I try to run multiple applications, using 4 cores each, only the first application is running(with 2,1,1 cores used in corresponding slaves). Every other application is going to WAIT state. Following the solution

HiveContext in SparkSQL - concurrency issues

Hi, I've been trying to use HiveContext(instead of SQLContext) in my SparkSQL application and when I run the application simultaneously, it only works on the first call and every other call throws the following error- ERROR Datastore.Schema: Failed initialising database. Failed to start