[try-II]

On Fri, Mar 23, 2018 at 6:43 AM, Tim Bradshaw <tfb@tfeb.org> wrote:

On 22 Mar 2018, at 21:05, Bakul Shah <bakul@bitblocks.com> wrote:

I was thinking about a similar issue after reading Bradshaw's
message about FORTRAN programs being critical to his country's
security. What happens in 50-100 years when such programs have
been in use for a long time but none of the original authors
may be alive? The world may have moved on to newer languages
and there may be very few people who study "ancient" computer
languages and even they won't have in-depth experience to
understand the nuances & traps of these languages well enough.
No guarantee that FORTRAN will be in much use then! Will it be
like in science fiction where ancient spaceships continue
working but no one knows what to do when they break?

My experience of large systems like this is that this isn't how they work at all. The program I deal with (which is around 5 million lines naively (counting a lot of stuff which probably is not source but is in the source tree)) is looked after by probably several hundred people. It's been through several major changes in its essential guts and in the next ten years or so it will be entirely replaced by a new version of itself to deal with scaling problems inherent in the current implementation. We get a new machine every few years onto which it needs to be ported, and those machines have not all been just faster versions of the previous one, and will probably never be so.

What it doesn't do is to just sit there as some sacred artifact which no-one understands, and it's unlikely ever to do so. The requirements for it to become like that would be at least that the technology of large-scale computers was entirely stable, compilers, libraries and operating systems had become entirely stable and people had stopped caring about making it do what it does better. None of those things seems very likely to me.

(Just to be clear: this thing isn't simulating bombs: it's forecasting the weather.)

+1 - exactly

point.

We have drifted a bit from pure UNIX, but I actually do think this is relevant to UNIX history. Once UNIX started to run on systems targeting HPC loads where Fortran was the dominate programming language, UNIX quickly displaced custom OSs and became the dominant target even if at the beginning of that transition

the 'flavor' of UNIX did vary (we probably can and should discuss how that happened and why independently

-- although

I will point out the UNIX/Linux implementation running at say LLNL != the version running at say Nasa Moffitt). And the truth is today, for small experiments you probably run Fortran on Windows on your desktop. But for 'production' - the primary OS for Fortran is a UNIX flavor of some type and has been that way since the mid-1980s - really starting with the UNIX wars of that time.

As I also have said here and elsewhere, while HPC and very much its lubricant, Fortran, are not something 'academic CS types' like to study these days

- even though

Fortran (HPC) pays my

and many of our

salar

ies

. Yet it runs on the system the those same academic types all prefer - i.e. Ken and Dennis' ideas. The primary difference is the type of program the users are running. But Ken and Dennis ideas work well for almost all users and spans

specific

application market

Here is a

picture

I did a few years ago for a number of Intel exec's. At the time I was trying to explain to them that HPC is not a single style of application and also help them understand that there two types of value - the code itself and the data. Some markets (

e.g.

Financial) use public data but the methods they use

to crunch it

(

i.e. the

code

)

are

private, while others

market segments

might have private data (e.g.

oil and gas) but

different customers

use the same or similar codes to crunch it.

or this discussion, think about how much of the code I sho

below is complex arithmetics -

while

much of it is searching

google style

, but a lot is

just plain

nasty math. The 'nasty math' that has not changed

over the years

and thus those codes are dominated by Fortran.

[Note Steve has pointed out that with AI maybe the math could change in the future - but certainly so far, history of these markets is basically differential equations solvers].

As Tim says, I really can not

see

that changing and

the

reason (I believe) is I do not see any

compelling

economic reason to do so.

Clem

ᐧ