Given a fork (f g h) f and h can be processed in parallel. But if f and h have side effects (shared global names that are modified) then they should not run in parallel. A programming practice that should be avoided anyway. This is not a pipeline, but multiple processors could be used. But even not running them in parallel I see nothing stating which, f or h, is run first. So one should avoid code that depended on the order of f and h execution anyway.
On Sat, Sep 26, 2015 at 4:42 PM, Raul Miller <[email protected]> wrote: > On Sat, Sep 26, 2015 at 3:04 PM, Vijay Lulla <[email protected]> wrote: > > quite easy. But what I'm very unclear about is how does one do > > pipelining in J? Say we have functions f, g, and h (all used > > monadically) and it is applied like f@g@h y and function g was > > particularly costly how can we parallelize (maybe the user has to > > program it himself or the interpreter can do some cost analysis [like > > query planning in SQL databases]) it to make it faster? Isn't this > > what the presenters were mentioning when they were using the example > > of airbus pipeline system? > > "Pipelining" seems to describe a variety of topics. > > https://en.wikipedia.org/wiki/Pipeline_(computing) > > So, I would have to say that there is no general technique. If f, g > and h are black boxes, you cannot pipeline them. If you want to > reschedule g or make it more efficient, you'll need to know details > about g. The more you know, the greater the odds are that you can do > it (or the important parts of it) differently, in a more efficient > manner. > > That said, I should also point out that a lot of the automated query > planning systems are workarounds for bogus constraints underlying the > sql standard. That effort could have gone in much more useful > directions if people hadn't bought into those ideas. (But at this > point, it has turned into a multi-billion dollar industry, so it's not > going away. And there are some applications where the flaws are not > all that important.) > > 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
