On Thu, Feb 21, 2013 at 4:47 PM, James Swaine < james.swa...@eecs.northwestern.edu> wrote:
> I think the problem (in addition to the ones I mentioned in my previous > message) is the use of let*, etc. inside your future thunk. > This seems suspicious to me. Probably if that is really the case, we should fix it. Robby > These were expanding to define-values, which seemed to be the source of > the `values' barricading. If you rewrite `render-scene-dummy' like so: > > (define (render-scene-dummy object-list) > (let* ([f (future > (lambda () > (define x (/ screen-width 2)) > (define y screen-height) > (define ray-res (ray-cast x y sph-vec)) > (define pix-col (point-col (int-res-p ray-res))) > #t))]) > (for* ([x (in-range (/ screen-width 2) screen-width)] > [y screen-height]) > (let* ([ray-res (ray-cast x y sph-vec)] > [pix-col (point-col (int-res-p ray-res))]) > #t)) > (touch f)) > ) > > I don't see any blocks on my machine. Are you still in experimentation > mode with futures? It seems there won't be much parallelism in this > program because you are only creating the one future. > > In general, it's better to restrict the use of futures to the hottest > parts of your program; variables that will be uniform across all parallel > tasks should be defined outside the thunk. > > > Date: Fri, 22 Feb 2013 00:03:28 +0300 >> From: Dmitry Cherkassov <dcherkas...@gmail.com> >> To: users@racket-lang.org >> Subject: [racket] values primitive blocks future execution >> Message-ID: >> <CAN0j1dRCGY7A2WxXBYXP= >> jblntw_-l3o7eoyjvd1vtab+qd...@mail.gmail.com> >> Content-Type: text/plain; charset="utf-8" >> >> Hi list. >> I've been doing a simple ray tracer[1] and decided to parallelize it using >> futures. >> >> I've tried to use flonums everywhere and added (in-range) to loops [3] >> (over x and y coordinates). >> >> The problem is that execution of future is blocked seriously. >> (apparently by the value primitive) [2] >> >> Are there any ideas why it doesn't work? >> >> I use racket v5.3.3. >> >> [1] Complete source code: http://pastebin.com/EGSzR1Tv >> >> [2] Future visualizer screenshot: http://ompldr.org/vaGpiaQ >> Invoked via >> (require future-visualizer) >> (visualize-futures (run-no-render)) >> >> [3] Source code for main loop: >> (define (render-scene-dummy object-list) >> (let* ([f (future >> (lambda () >> (for* ([x (in-range (/ screen-width 2))] >> [y (in-range screen-height)]) >> (let* ([ray-res (ray-cast x y object-list)] >> [pix-col (point-col (int-res-p ray-res))]) >> #t)) >> ))]) >> >> (for* ([x (in-range (/ screen-width 2) screen-width)] >> [y (in-range screen-height)]) >> (let* ([ray-res (ray-cast x y object-list)] >> [pix-col (point-col (int-res-p ray-res))]) >> #t)) >> (touch f))) >> >> >> >> -- >> With best regards, >> Dmitry >> -------------- next part -------------- >> An HTML attachment was scrubbed... >> URL: < >> http://lists.racket-lang.org/users/archive/attachments/20130222/6e2262a8/attachment-0001.html >> > >> > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users > >
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