About memory allocation

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odwrotnie - 03 Mar 2006 11:42 GMT

I am wondering if an object is bigger if it has a lot of methods.
If You dont know mayby You can tell me where can I find informations about
memory allocation process?

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Best regards,
Odwrotnie.

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Green - 03 Mar 2006 14:29 GMT

Memory is typically divided into 3 parts:

1. Code segment (your code goes here)
2. Heap/Data (objects live here)
3. Stack (threads live here)

So if your objects has lots of methods it affects only the code segment
and not your heap. But if your object has lots of member variables then
your objects will be bigger and hence your heap will be affected.

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Roedy Green - 03 Mar 2006 15:15 GMT

>I am wondering if an object is bigger if it has a lot of methods.
>If You dont know mayby You can tell me where can I find informations about
>memory allocation process?

no the object size depends on the fields it has, not the methods. The
object has a pointer to a vtbl which points to the code for the
methods so there in no extra per-method overhead on the object itself.

You can get the source for the JVM and have a look.

see http://mindprod.com/jgloss/jdk.html for the link. You have to sign
some sort of agreement first.

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Canadian Mind Products, Roedy Green.
http://mindprod.com Java custom programming, consulting and coaching.

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Roedy Green - 03 Mar 2006 15:16 GMT

On Fri, 03 Mar 2006 15:15:16 GMT, Roedy Green
<my_email_is_posted_on_my_website@munged.invalid> wrote, quoted or
indirectly quoted someone who said :

>You can get the source for the JVM and have a look.
>
>see http://mindprod.com/jgloss/jdk.html for the link. You have to sign
>some sort of agreement first.

I have never done this myself, though I would love to peek. The reason
is, once you do, you are no longer legally permitted to work on
alternate JVMs.

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Canadian Mind Products, Roedy Green.
http://mindprod.com Java custom programming, consulting and coaching.

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Tony Morris - 04 Mar 2006 01:11 GMT

> On Fri, 03 Mar 2006 15:15:16 GMT, Roedy Green
> <my_email_is_posted_on_my_website@munged.invalid> wrote, quoted or
[quoted text clipped - 8 lines]
> is, once you do, you are no longer legally permitted to work on
> alternate JVMs.

You are permitted to work on alternate JVMs, only there are various
restrictions under a licence agreement, for example, using a 'cleanroom'
in certain circumstances. I recently left my job working on the IBM JVM
(specifically, the API spec. implementation), but I won't forget working
on the JCE implementation, never being permitted to look at the Sun
source, but the fellow who sat near me could. It's all a big circus
show, even ignoring the flaws of copyright legislation.

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Tony Morris
http://tmorris.net/

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odwrotnie - 06 Mar 2006 13:48 GMT

Thank You very much!

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Best regards,
Odwrotnie.

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About memory allocation

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