> How many vCores allocated for Tasks within the Executors?
Tasks run inside pre-allocated Executors, and do not cause further allocations to occur.
Read on below to understand the relationship between tasks and executor from a resource and concurrency viewpoint:
""" Every Spark executor in an application has the same fixed number of cores and same fixed heap size. The number of cores can be specified with the --executor-cores flag when invoking spark-submit, spark-shell, and pyspark from the command line, or by setting the spark.executor.cores property in the spark-defaults.conf file or on a SparkConf object. Similarly, the heap size can be controlled with the --executor-memory flag or the spark.executor.memory property. The cores property controls the number of concurrent tasks an executor can run. --executor-cores 5 means that each executor can run a maximum of five tasks at the same time. """ Read more at http://blog.cloudera.com/blog/2015/03/how-to-tune-your-apache-spark-jobs-part-2/