[racket] Futures and shared data structure

From: Robby Findler (robby at eecs.northwestern.edu)
Date: Mon Dec 20 13:54:50 EST 2010

I'm not sure about the uncollectable issue, but for the rest, try
running in racket, enabling the debug log. Eg, if you save the file in
x.rkt and do this:

  racket -W debug x.rkt

then you should see some messages telling you what is causing your
future to get stuck.

Also, do be sure to read this if you haven't yet:



On Mon, Dec 20, 2010 at 12:47 PM, Eduardo Bellani <ebellani at gmail.com> wrote:
> Hello all
> I am trying to understand futures, and I have generated to following
> code to see how I would create reader futures. Unfortunately my futures
> are not running in parallel and are taking more time that the serial
> version. Besides that it seems to capture the vector in a way that it
> becomes noncollectable by the GC.
> Could anyone give some hints as to why? (my version is "5.0.2" on Linux)
> #lang racket
> (require racket/future rackunit rackunit/text-ui)
> (define DATA (make-vector 99999999 'datum))
> (define-test-suite read-from-shared
>  (test-suite "with futures"
>              (check-equal?
>               (time (let ([f (future (λ _ (read-data DATA)))])
>                       (touch f)
>                       (read-data DATA)))
>               (void)))
>  (test-suite "no futures"
>              (check-equal?
>               (time (read-data DATA)
>                     (read-data DATA))
>               (void))))
> (define (read-data some-data)
>  (for ([i (in-vector some-data)]) i))
> (run-tests read-from-shared)
> Thanks
> --
> Eduardo Bellani
> omnia mutantur, nihil interit.
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