[Vm-dev] Re: [Pharo-project] is it possible to know the memory
occupation (bytes) of an object?
Mariano Martinez Peck
marianopeck at gmail.com
Mon Sep 27 19:20:05 UTC 2010
On Wed, Sep 22, 2010 at 12:34 PM, Mariano Martinez Peck <
marianopeck at gmail.com> wrote:
> On Wed, Sep 22, 2010 at 12:12 PM, Henrik Johansen <
> henrik.s.johansen at veloxit.no> wrote:
>> On Sep 22, 2010, at 9:59 40AM, Adrian Lienhard wrote:
>> > Some notes:
>> > - What should be answered for small ints? 1 sizeInMemory -->8. That's
>> wrong. Shouldn't this answer 0?
>> Philosophical question really, imo both 4 (Again, in 32bit images at
>> least) and 0 would be "correct" answers in their own ways. 8 is definitely
>> wrong though :)
>> The method comment should probably highlight which definition is used.
So....what should we consider for SmallInteger ? 4 bytes or 0 bytes?
I would like to compute the really used memory.
> At the beginning I also thought to have 4, instead of 0. The problem is
> that if you put 4 and you have an object with and instVar that it is a
> SmallInteger, it will be counted twice, when actually it is only one.
> That's why I thoguht 0 was better, since I want the really occupated
> memory. On the other hand, if you do "4 sizeInMemory" and see zero, I have
> to admit it is a litlte confusing.
> The problem is that if I do for example:
> Class >> spaceForInstances
> | totalSize |
> totalSize := 0.
> self allInstancesDo: [ :inst |
> totalSize := totalSize + inst sizeInMemory.
> ^ totalSize
> SmallInteger spaceForInstances ->> 0
> So I don't know...maybe we have to answer 4 instead of 0?
> Adrian what do you think?
>> > - In the line contentBytes := contentBytes + (self basicSize *
>> bytesPerElement), why is contentBytes added because it should be always 0
>> because self class instSize should return 0 in case of variable classes. Or
>> do I miss something?
>> You can have instance variables in variable classes:
>> ArrayedCollection variableSubclass: #TallyArray
>> instanceVariableNames: 'tally'
>> classVariableNames: ''
>> poolDictionaries: ''
>> category: 'Collections-Arrayed'
>> TallyArray instSize 1
>> (TallyArray new: 5) basicSize 5
>> Sure, they're not used very often in Squeak/Pharo since become: is so
>> slow, but there's no theoretical reason why you can't for example implement
>> Set as a variable subclass with a tally inst var.
>> > - Please remove the inline comment "inst vars"; if a comment is needed
>> it should go into the main comment.
>> I agree, should be self-explanatory.
>> Pharo-project mailing list
>> Pharo-project at lists.gforge.inria.fr
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the Vm-dev