[racket] Racket Virtual Machine runs out of memory

Btw, I have a boolean vectors library that you can use as is or as a
starting point. I cannot send it to you until monday, but you can find
an old copy in the archives of this ml, googling for my name + boolean
vector.



2012/7/20, Harry Spier <vasishtha.spier at gmail.com>:
> Thanks Eli,
>
> I probably have to go the route you and others suggest.  But I think I
> still have a problem.  Even the single operation of MagickExportPIxels
> to export the pixel data of this page to manipulate fills at least 4/7
> of the memory before failure.  And there is no guarantee that pages
> wont have more pixel data.  They probably will.  And as Matthias says
> the list doesn't seem "that large".
>
> Also I have 4 or 5 transformation stages of the pixel data.  Will
> putting in Garbage Collection commands to get rid of transformations
> of the data I've already used help?
>
> What sets the amount of memory the Racket virtual machine uses.  Is it
> a Racket parameter, Is it a function of the amount of RAM in the
> machine?  Is this more a Windows problem and will switching to Linux
> help etc.?
>
> Harry Spier
>
> On Fri, Jul 20, 2012 at 1:09 PM, Eli Barzilay <eli at barzilay.org> wrote:
>> 10 minutes ago, Harry Spier wrote:
>>> #lang racket
>>> (define l (time (build-list (* 7091 5023) (λ (x) 1))))
>>> (system "PAUSE")
>>>
>>> ABORTS with Racket Virtual Machine run out of memory
>>
>> IME, the exact size where things fail is not important -- if you're
>> getting anywhere close to it, then you should revise the code to use
>> less memory.
>>
>> There was the option that was raised for using integers, which might
>> be inconvenient -- even with one (huge) integer for each row.
>> Instead, I think that it would be convenient to use one big byte
>> string for the whole array, and write some accessor functions to
>> address the contents as a matrix.  The exact format of the byte string
>> can be one byte per 1/0 pixel or even more compactly, one bit per
>> pixel.  The choice should depend on whatever libraries you're using
>> with the same data, to minimize translation work.  (Dealing with bits
>> will make the access code a bit more complicated.)
>>
>> Currently, you're using one cons cell for each number, which is
>> probably somewhere around 3 pointers -- which is about 12 bytes per
>> bit.  So just a one byte for each number would be a 12x factor, with
>> one bit per 1/0, you're at ~100x saving, which would be significant
>> enough to reduce other processing times.
>>
>> --
>>           ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
>>                     http://barzilay.org/                   Maze is Life!
>
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