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From Kris Schneider <k...@dotech.com>
Subject Re: [OT] how to calculate the size of an object
Date Thu, 08 Jul 2004 19:49:32 GMT
Not too surprising that it's available through a native programming interface
(JVMTI) since it's really an implementation-dependent metric:

http://java.sun.com/j2se/1.5.0/docs/guide/jvmti/jvmti.html#GetObjectSize

Quoting Brian Lee <brian_a_lee@hotmail.com>:

> If you run this from a simple console test app, the JVM won't allocate any 
> extra objects between 2 and 4.
> 
> Unfortunatly, this is the most exact way to find out memory usage 
> (serialization size doesn't necessarily mean in memory size).
> 
> Just wait til those slackers at Sun at a Object.sizeof() method in jdk1.9 or
> 
> something lame.
> 
> BAL
> 
> >From: Navjot Singh <navjot.s@net4india.net>
> >To: Struts Users Mailing List <user@struts.apache.org>
> >Subject: Re: [OT] how to calculate the size of an object
> >Date: Thu, 08 Jul 2004 22:16:12 +0530
> >
> >hi,
> >
> >Thanks for the link but this is very naive way of doing it. I am leaving it
> 
> >to the mercy of gc.
> >
> >What this method is doing
> >
> >1. run gc() manually (AND hope it wont run automatically again soon.)
> >2. free memory
> >3. create and object.
> >4. free memory
> >
> >and now just wish that JVM wont allocate any memory in it's heap between 
> >steps 2 & 4. so that one can assume that whatsoever output comes belongs to
> 
> >my object. I am at something better.
> >
> >Jim you are absolutely right, this technique may return a negative number.
> >
> >navjot singh
> >
> >
> >DGraham@EvergreenInvestments.com wrote:
> >
> >>
> >>http://www.google.com/search?hl=en&lr=&ie=UTF-8&q=size+java+object
> >>
> >>The first one looks promising.
> >>
> >>Dennis
> >>
> >>
> >>
> >>
> >>*Navjot Singh <navjot.s@net4india.net>*
> >>
> >>07/08/2004 11:57 AM
> >>Please respond to
> >>"Struts Users Mailing List" <user@struts.apache.org>
> >>
> >>
> >>
> >>To
> >>	Struts Users Mailing List <user@struts.apache.org>
> >>cc
> >>
> >>Subject
> >>	[OT] how to calculate the size of an object
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>hi,
> >>
> >>I use SAX parser to load an LDIF file into memory. Whatsoever data i
> >>read, i fill into an object.
> >>
> >>I need to know *the size of LDIFData object* at runtime. How to do that?
> >>
> >>Well the class structure is something like this
> >>
> >>public class LDIFData{
> >>                 ArrayList cards; // collection of Card
> >>                 String filename;
> >>                 long lastLoadedTime;
> >>}
> >>
> >>public class Card{
> >>                 String name;
> >>                 String email
> >>                 String mobile;
> >>}
> >>
> >>--
> >>regards
> >>Navjot Singh
> >>
> >>When you jump for joy, beware that no-one moves the ground from beneath
> >>your feet. -- Stanislaw Lem, "Unkempt Thoughts"
> >>
> >>---------------------------------------------------------------------
> >>To unsubscribe, e-mail: user-unsubscribe@struts.apache.org
> >>For additional commands, e-mail: user-help@struts.apache.org
> >>
> >>
> >>
> >>------------------------------------------------------------------------
> >>
> >>---------------------------------------------------------------------
> >>To unsubscribe, e-mail: user-unsubscribe@struts.apache.org
> >>For additional commands, e-mail: user-help@struts.apache.org
> >
> >--
> >regards
> >Navjot Singh
> >
> >When you jump for joy, beware that no-one moves the ground from beneath
> >your feet. -- Stanislaw Lem, "Unkempt Thoughts"

-- 
Kris Schneider <mailto:kris@dotech.com>
D.O.Tech       <http://www.dotech.com/>

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