[plt-scheme] sizeof

I remember getting zeroes intermittently when I tried using current-memory-use with a custodian before (about a year ago).

This is for a web app, so there is a custodian structure already in place. It looks like (current-memory-use (current-custodian)) returns a fairly constant value that changes occasionally and by large increments (every 20 or 30 page loads). Perhaps this is blocks of allocated memory rather than precise consumption?

I've written a little combinator library that traverses the relevant structures and estimates their size directly... this is undoubtedly a naive approach, especially as I have no idea about PLT internals and I haven't done any C level programming in years.

I'm only trying to get a rough idea of memory use, to point out any pages with gross inefficiencies. The naive approach may be enough for this.

-- Dave

On 5 Jan 2010, at 16:23, Robby Findler wrote:

> It doesn't look like it, but I may be doing something wrong (the
> printf is just there to be usre that the object is still in used).
> 
> (let ([c (make-custodian)])
>    (parameterize ([current-custodian c])
>      (let ([obj (cons 1 2)])
>        (collect-garbage)
>        (begin0
>          (current-memory-use c)
>          (printf "~s\n" obj)))))
> 
> This produces 0 for me.
> 
> Robby
> 
> On Tue, Jan 5, 2010 at 10:18 AM, Jay McCarthy <jay.mccarthy at gmail.com> wrote:
>> Could you create it in a new custodian and measure that custodian memory usage?
>> 
>> Jay
>> 
>> On Tue, Jan 5, 2010 at 8:00 AM, Robby Findler
>> <robby at eecs.northwestern.edu> wrote:
>>> You can create a bunch of them and compare the amount of memory used
>>> before and afterwards (and divide).
>>> 
>>> Robby
>>> 
>>> On Tue, Jan 5, 2010 at 8:53 AM, Dave Gurnell <d.j.gurnell at gmail.com> wrote:
>>>> Hi all,
>>>> 
>>>> Is there a simple way of estimating the number of bytes of RAM that a particular piece of data is occupying?
>>>> 
>>>> e.g.
>>>> 
>>>>    (sizeof some-large-data-structure) ; ==> 1024 bytes
>>>> 
>>>> I saw the sizeof package on PLaneT but it looks like that's for FFI structures, not scheme ones.
>>>> 
>>>> Many thanks,
>>>> 
>>>> -- Dave
>>>> 
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>> 
>> 
>> 
>> --
>> Jay McCarthy <jay at cs.byu.edu>
>> Assistant Professor / Brigham Young University
>> http://teammccarthy.org/jay
>> 
>> "The glory of God is Intelligence" - D&C 93
>>