In short:
Does it worth the effort to add multithreading scalability (Vertical scalability) on an application that will run always in a MPP infrastructure such Tandem HPNS (Horizontal scalable)?
Now, let me go deeper:
I’ve seen on many places the development under MPP (Massively Parallel Processing) using Java tend to think, if it’s Java you can use all what Java provides (You know, Write once run anywhere!) in which multithreading libraries(such threads, AKKA, Thread Pools, etc.) can help a lot by speeding up the performance using parallelism.
Forgetting the fact, if it’s MPP, it is horizontal scalable, meaning if you need a faster app, you have to design it to run multiples copies of the application, each on a different processor.
On the other side we have SMP (Symmetric Multi-processing) infrastructures (here we have any windows, Linux, UNIX like environment), in these you don’t have to worry about that, since the scalability is vertical, you can have more threads in which their execution will be distributed on the different cores the OS have available (Here I do agree on using Multithread libraries).
So, having this in mind, my question is, if there is a need of creating an application that will perform a heavy load of data with a lot of validations and other requirements in which the use of parallelism will help a lot to improve the load time, but, it has to run under a MPP environment (such Tandem HPNS).
Should the developer invest time on adding Multithread libraries to add parallelism and concurrency?
Just a couple of side notes:
1) I’m not saying SMP is better or MPP is better, they are just different infrastructures; my point goes just to the use of multithread libraries on MPP environments giving the fact an application using multithread on MPP will use just one CPU of the N Cpus the Server may has.
2) I’m not saying the MPP server does not support multithread libraries, you can have multithreads running on HPNS, but even you have 20 threads, there is no real parallelism since one thread is blocking the others; unless you have the application distributed (several copies running) on different CPUs.
No I don't think it makes sense to add multithreaded scalability on application that will always run on tandem, because tandem does not provide kernel level thread so even though you write multithreaded application it will not give any benefit.
Even tandem HPNS Java provides multithreading as per Java Spec but its performance is not comparable with linux or any other OS which support kernel level threading. Actual purpose of tandem is HA availability because of its hardware redundancy.