Should kill running Spark Jobs when a query is cancelled. When a query is cancelled, Driver.releaseDriverContext will be called by Driver.close. releaseDriverContext will call DriverContext.shutdown which will call all the running tasks' shutdown.
since SparkTask didn't implement shutdown method to kill the running spark job, the spark job may be still running after the query is cancelled. So it will be good to kill the spark job in SparkTask.shutdown to save cluster resource.