Jim, all your replies in the three separate emails - make valid points and give me some food for thought. Thanks.
On Wed, Oct 14, 2020 at 3:10 PM Lux, Jim (US 7140) <james.p....@jpl.nasa.gov> wrote: > > > > > *From: *Beowulf <beowulf-boun...@beowulf.org> on behalf of Oddo Da < > oddodao...@gmail.com> > *Date: *Wednesday, October 14, 2020 at 11:09 AM > *To: *Michael Di Domenico <mdidomeni...@gmail.com> > *Cc: *"beowulf@beowulf.org" <beowulf@beowulf.org> > *Subject: *[EXTERNAL] Re: [Beowulf] ***UNCHECKED*** Re: Spark, Julia, > OpenMPI etc. - all in one place > > > > On Wed, Oct 14, 2020 at 1:24 PM Michael Di Domenico < > mdidomeni...@gmail.com> wrote: > > On Wed, Oct 14, 2020 at 11:53 AM Oddo Da <oddodao...@gmail.com> wrote: > > i'll agree that in some respects software engineering has gotten > better in the last 20yrs, but it's subjective. there are a lot of > things that have gotten better and there are a lot of things that are > much worse. but i'm not sure you can apply that statement to HPC. > HPC code doesn't churn like business code or even more volatile cloud > code. HPC code is usually written to solve something specific and > gets incremental updates over time. usually that something specific > hasn't changed the last 20yrs (think physics/chemistry) the models we > use to describe or solve the problems likely have, but the underlying > code is probably basically the same with tweaks along the way to fit > the new model. > > > > I disagree. I think yes, there is old code that does not churn but there > are always new people/grad students coming into the field. They too are > being pointed in the same direction of how to do things, which is what we > are discussing here ;-) > > > > > > > > Yes, there are new people coming in. But they’re not developing new > modeling codes from scratch – they’re typically “improving” the existing > codes. And as Michael pointed out, there’s significant resistance to > change when you’ve got a code base that is known, debugged, and has known > warts. Big changes occur when a modeling paradigm shift occurs. And > those are not real common. > > > > > > > > > > > > an evolution to MPI. but it goes back to technical debt. to re-write > something in chapel is non-trivial and may not be worth the time. > writing something new and choosing chapel is really left up to the > developer. i have some chapel users here and there, but they're a > minority. and since chapel is largely only found on cray machines its > exposure is low > > > > It seems that in your world nothing new ever gets written? You are talking > only about re-writes ;). > > > > For many HPC science applications this is true – Physics models change > very slowly. Once you have a gridded finite element model, it “just works” > and there’s not huge demand for new modeling approaches. > > > > Changes in language usage usually occur because of a technical problem > with the existing code that means it just cannot be modified. More than > one ambitious person has said “let’s re-do program X from Fortran to C++ or > Java or Ada or Python” and found it a bigger challenge than expected. > There is a definite preference for the devil you know. > > > > > > > > > > >
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