Well, I think that low rank verbs working on higher rank data are easily parallellizable (see for instance: http://www.jsoftware.com/jwiki/MarshallLochbaum/Parallelize , in my uninformed opinion, the same can work on other PC's as well).
The overhead issue is always there, and it is up to the user to not apply parallellization for things that are not worth parallellizing. The dependency and caching problem is a harder nut to crack. In Matlab, they sort of solved the issue introducing different classes of variables when using parallel for-loops: http://www.mathworks.nl/help/distcomp/advanced-topics.html#bq_of7_-1 . A similar thing might be concocted in J using ranks, and enforced through preprocessing of the code being run. It's not perfect though, I've seen lots of errors mixing this with pass-by-reference object oriented programming, but it gets a long way already. Just my 2 cents. Jan-Pieter 2014-02-22 15:14 GMT+01:00 Don Guinn <[email protected]>: > The J notation is already for multiprocessing on multiprocessing computers > with shared memory. Each is just one example. When the rank of a verb is > less than the rank of its nouns can multiprocess. > > Problems I see to expanding J to multiprocessing: > > 1: Any user definitions with side effects like using global names can fail. > > 2: Computer now use cache memories. Cache works well when the cache of one > processor is not being updated by another processor. This is not much of a > problem when dealing with unrelated tasks; however, J multitasking involves > multitasking related tasks. So cache update collisions are much more likely > and could really slow down processors. > > 3: The dispatching and cleanup for multiprocessing overhead might exceed > the time saved for short running verbs. > > I would hate to see new conjunctions and adverbs added to J to support > multiprocessing as the existing ones are already so ready for > multiprocessing. Then the problem becomes how for the interpreter to know > when to multiprocess and when to not. > > > On Sat, Feb 22, 2014 at 1:07 AM, Jack Andrews <[email protected]> wrote: > > > What's an example of notation that might help concurrent computing? In > k, > > there's peach (parallel each) which seems to be adequate. > > > > On Friday, February 21, 2014, Raul Miller <[email protected]> wrote: > > > > > J is currently an excellent tool for developing those skills, but if > any > > of > > > us have implemented J as a notation for homogeneous computations on > > > computing clusters, I've not heard about it. > > > > > > And that's a shame. We have a lot we could offer people but we need to > > > clean up our act if we are going to succeed there. > > > > > > Thanks, > > > > > > -- > > > Raul > > > > > > > > > > > > > > > On Thu, Feb 20, 2014 at 11:13 AM, robert therriault > > > <[email protected] <javascript:;>>wrote: > > > > > > > Nice work Raul, > > > > > > > > I agree with Joe that it is key that the audience be identified, the > > next > > > > step beyond that is finding a way to get the production in front of > > that > > > > audience...gasp...marketing. > > > > > > > > For now the best suggestion I have is to move your author's note to > the > > > > top and make it an abstract. I think it sets the tone and the > > motivation > > > > for the reader really well. > > > > > > > > On the employment issue, I think that people with skills in big data > > are > > > > in demand ... and that J is an excellent tool to develop and execute > > > those > > > > skills. > > > > > > > > Cheers, bob > > > > > > > > On Feb 20, 2014, at 7:41 AM, Raul Miller <[email protected] > > <javascript:;>> > > > wrote: > > > > > > > > > On Thu, Feb 20, 2014 at 10:33 AM, Joe Bogner <[email protected] > > <javascript:;> > > > > > > > > wrote: > > > > > > > > > >> I think the essay is fairly technical in nature and requires a > > fairly > > > > steep > > > > >> baseline of knowledge. I agree that it might be helpful to > identify > > > the > > > > >> audience up front. Maybe even have a "Why J?" for different types > > of > > > > >> audiences > > > > >> > > > > > > > > > > In terms of wiki structure, perhaps urls with > > Essays/WhyJ/AudienceType > > > > > might work. > > > > > > > > > > That said, I am limited in my own vision (which is spread a bit > thin > > > > right > > > > > now). > > > > > > > > > > If anyone wants to propose their own draft and/or piggy back their > > > vision > > > > > on mine (or even replace mine - I have no problem taking a back > > seat), > > > > > please feel free. > > > > > > > > > > Thanks, > > > > > > > > > > -- > > > > > Raul > > > > > > > ---------------------------------------------------------------------- > > > > > For information about J forums see > > http://www.jsoftware.com/forums.htm > > > > > > > > > ---------------------------------------------------------------------- > > > > For information about J forums see > http://www.jsoftware.com/forums.htm > > > > > > > ---------------------------------------------------------------------- > > > For information about J forums see http://www.jsoftware.com/forums.htm > > > > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
