Object size and limits

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2 total messages Started by Kjartan Emilsson Wed, 09 Sep 1992 13:29

#872

Author: Kjartan Emilsson
Date: Wed, 09 Sep 1992 13:29

20 lines
1090 bytes

Hi!
Here are a few questions I would be interested in knowing the answers to,  
if somebody knows them:

How can you estimate the memory usage of an instance of an object in a  
program, beside using NXWriteObject and looking at the file size ? Is it  
the size of the declared instance variables plus method selectors, or are  
there some additional headers ? Are there any limits to the number of  
instances of objects and to the number of loaded classes in a program  
besides simple memory limitations ?

Is there any bottleneck in the run-time system when the number of  
instances/classes increases ?

I'm thinking of order of magnitudes like about 5000 instances of 500+  
classes/categories.

Thanks,

-Kjartan

Re: Object size and limits

#900

Author: MKK2
Date: Wed, 09 Sep 1992 19:28

19 lines
1205 bytes

In article <28935@sophia.inria.fr>, kjartan@kurosawa.cica.fr (Kjartan Emilsson)
says:

>How can you estimate the memory usage of an instance of an object in a
>program, beside using NXWriteObject and looking at the file size ? Is it
>the size of the declared instance variables plus method selectors, or are
>there some additional headers ? Are there any limits to the number of

As I understand it, instances are essentially structs, so sizeof
tells you pretty much what you want to know.  Yes, the code for
the methods and the selector tables require some overhead, but they
are not duplicated for each instance.

>I'm thinking of order of magnitudes like about 5000 instances of 500+
>classes/categories.

If you feel comfortable that your design really needs 500 classes, I don't
forsee any bottleneck.  5000 instances should be no problem.

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