[Beowulf] [EXTERNAL] Re: ***UNCHECKED*** Re: Spark, Julia, OpenMPI etc. - all in one place

[Jim Cownie]

One more point, which may already have been made, but in case not…
You are asking (my paraphrase…) 
* “Why hasn't MPI been replaced with something higher level?”
* “Why hasn't Fortran been replaced with something higher level?”

In that context, it seems worth pointing out that 
* Fortran is much higher level than it used to be (e.g. operation on whole arrays without needing loops was certainly not in FORTRAN IV or Fortran 77)
* Since Fortran 2008, it has had support for the co-array features which mean that you can write distributed memory codes without (explicitly) using MPI, and with a syntax that looks like array indexing, rather than message passing.

There’s a general educational issue here, which is that it is much easier for people to recognise that they need education to understand something if that thing is something they only just heard about, whereas even if it has many new features, if it’s something whose name they already know (and which they did a course in 15 years ago) then they think they already know all about it.
Fortran clearly suffers from this, but so do C++, OpenMP, … 

-- Jim
James Cownie <jcownie at gmail.com>
Mob: +44 780 637 7146

> On 15 Oct 2020, at 12:07, Oddo Da <oddodaoddo at gmail.com> wrote:
> 
> On Thu, Oct 15, 2020 at 1:11 AM John Hearns <hearnsj at gmail.com> wrote:
> This has been a great discussion. Please keep it going. 
> 
> I am all out of ammo ;). In all seriousness, it is not easy to ask these questions because it kind of can be interpreted as offensive - in a nutshell, people may perceive what I am asking as "what have y'all been doing for 20 years? Nothing?".
>  
> To the points on technical debt, may I also add re-validation?
> Let's say you have a weather model which your institute has been running for 20 years.
> If you decide to start again from fresh with code in a new language you are going to have to re-run known models
> and debate whether or not they fit within error bounds of the old model.
> That takes effort - which may of course be justified if you make gains in speed, flexibility or being able to use new hardware like GPUs.
> 
> I understand all this but, of course, not everything has to do what has been done. Hopefully, there are plenty of people entering the field or coming back to it, without any technical debt.
> 
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