I'm looking into this now, but there are a few modifications you can make
to eliminate some blocking calls, namely:
sph-list is a list, and you are using for/fold to iterate over the elements
in the list (inside a future). This is problematic for a number of reasons;
instead, you could convert it to a vector (or just change your definition
to use a vector) and change `ray-cast' accordingly:
(define (ray-cast x y object-list)
(let ([view-ray (screen-ray x y)])
(define closest-int (int-res #f 10000.0 null-point))
(for ([i (in-range 0 (vector-length object-list))])
(define obj (vector-ref object-list i))
(set! closest-int (get-closer-res closest-int
(hit-sphere3D view-ray obj))))
closest-int))
Also, there are two places where I think you may have forgotten to use
flonum primitives (on lines 99 and 100) -- just change `sqrt' to `flsqrt',
as you have done elsewhere in the code.
This doesn't eliminate all the blocking behavior, however -- I still see a
few `values' blocking calls, and allocation as well. I'll spend some more
time looking through it and report back to you.
Cheers,
James
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
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