Bluemix Spark and Hadoop Service Configuration

Question

Having run through configuration of both the Hadoop Big Insights and Apache Spark services on Bluemix, I noticed that Hadoop is very configurable.I have a choice of how many nodes there will be in the cluster and the RAM and CPU cores of those nodes as well as hard disk space

But the Spark service seems less configurable. The only choice I have is to choose between 2 and 30 Spark executors.

I am working with Bluemix as part of an IBM IC4 project to evaluate these services, so I have a few questions about this.

1. Is it possible to configure the Spark service in a similar way to the Hadoop service? i.e. choose nodes, RAM of nodes, CPU cores etc.

2. What are Spark executors in this context? Are they nodes? If so, what are their specifications?

3. Is there a plan to improve the options for Spark's configuration in the future?

Apologies for the questions but I need to know these specifications in order to carry out my work.

Answer 1

The Big Insights service is what some would call a hosted service. Which is to say, when you provision on instance of this service you get your own cluster with nodes configured as specified in the chosen plan. Consequently, you'll want to know exactly what each node you're paying for gives you. On the other hand, the Apache Spark service is a shared compute service, wherein you pay for compute to run your spark programs. Running spark is about in-memory compute, and creating RDDs over sources of data hosted by other data services. So in this context, what matters is how many concurrent jobs can I run and how many parallel tasks can I run with how much memory, and so on. In the Spark service plan, these executors seem to be an abstraction on this compute horsepower; unfortunately, hard for you to map that to physical hardware if you care about that. The plan description needs more elaboration and details about how one translates this abstraction to how you map to your workload needs.

However, I understand that this should be improved considerably at some point in the near future. There have been rumors about moving to only a single spark service plan where you can dial in, whenever you want, how much compute you need and that would take effect when you click "go", for all spark jobs from that point forward; it seems like you can twiddle the dials until you get what you want, see what that would cost, then lock it in until next time you need to change it. I can image something even more dynamic than that on a per-job basis. But anyway, seems like the direction things may be going for this compute service.