[racket] Futures and shared data structure

Oh. You have the touch first. Try putting it second.

Robby

On Mon, Dec 20, 2010 at 1:02 PM, Eduardo Bellani <ebellani at gmail.com> wrote:
> Thanks for the prompt reply.
>
> Disregard the noncollectable thing, that was a confusion on my side.
> Still, my doubt remains about why my futures version is slower and not
> parallel. I did read about the futures, but alas, I'm still in the dark
> as to why it is behaving like it is.
>
> My output to your suggested approach is
>
> GC [minor] at 1514740 bytes; 818464 collected in 4 msec
> GC [minor] at 2142928 bytes; 678980 collected in 4 msec
> GC [minor] at 4424700 bytes; 1509104 collected in 12 msec
> GC [minor] at 4999304 bytes; 614508 collected in 16 msec
> GC [minor] at 8337384 bytes; 1957728 collected in 20 msec
> GC [minor] at 10529324 bytes; 1709172 collected in 24 msec
> GC [minor] at 14245196 bytes; 2815768 collected in 28 msec
> GC [minor] at 19109972 bytes; 4515808 collected in 48 msec
> GC [minor] at 20287336 bytes; 4153060 collected in 32 msec
> GC [minor] at 416134292 bytes; -27108 collected in 1652 msec
> cpu time: 2660 real time: 2657 gc time: 1652
> cpu time: 1000 real time: 1001 gc time: 0
> 2 success(es) 0 failure(s) 0 error(s) 2 test(s) run
> 0
>
> Which for me is not helpful. Any more suggestions?
>
>
> On 12/20/2010 04:54 PM, Robby Findler wrote:
>> 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:
>>
>>   http://docs.racket-lang.org/guide/performance.html#%28part._effective-futures%29
>>
>> Robby
>>
>> 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.
>>> _________________________________________________
>>>  For list-related administrative tasks:
>>>  http://lists.racket-lang.org/listinfo/users
>
>
> --
> Eduardo Bellani
>
> omnia mutantur, nihil interit.
>