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From Clinton Begin <clinton.be...@gmail.com>
Subject Re: Estimating amount of memory need for cache
Date Fri, 22 Jul 2005 13:26:31 GMT
Good idea Michal,

Sounds like something useful that could be added to Commons Lang. Would you 
have an interest in contributing it, or are you going to make me write it? 
;-)

Cheers,
Clinton

On 7/22/05, Michal Malecki <misiek_x@poczta.onet.pl> wrote:
> 
> I think that in many cases estimating memory taken maybe quite easy (when 
> there are no circual references). Then it's ease to write utility that would 
> analyze object using reflection or to implement interface that has size() 
> method; If you know structure of the bean and there are well known types 
> (strings, primitives maybe dates/timestamps) estimating size is as easy as 
> writing hashCode :)
> Michal Malecki
> 
> ----- Original Message ----- 
> *From:* Clinton Begin <clinton.begin@gmail.com> 
> *To:* user-java@ibatis.apache.org 
> *Sent:* Friday, July 22, 2005 3:15 PM
> *Subject:* Re: Estimating amount of memory need for cache
> 
> Thanks for the info Michal,
> 
> I suppose then you'd have to double expected size of each string in your 
> model then, to make the estimate safer.
> 
> Too bad there isn't something along the lines of System.sizeOf (Object 
> obj). 
> 
> Cheers,
> Clinton
> 
> On 7/22/05, Michal Malecki <misiek_x@poczta.onet.pl> wrote: 
> > 
> > Hello,
> > I think it's not quite so e.g. all characters in the memory are 2 bytes 
> > and serialized there are in UTF-8
> > here is article about it:
> > http://www.javaworld.com/javaworld/javaqa/2003-12/02-qa-1226-sizeof.html 
> > 
> > Regards
> > Michal Malecki
> >  
> > 
> > You could serialize the results it to disk. That would give you a 
> > pessimistic estimation of the size it will be in memory. That is, the cost 
> > of serialization will be higher than the amount of RAM used, so you can feel 
> > relatively confident that it will be smaller in memory.
> > 
> > Cheers,
> > Clinton
> > 
> > On 7/21/05, Nathan Maves <Nathan.Maves@sun.com> wrote: 
> > > 
> > > What is the best and most accurate way to calculate the space needed
> > > to cache a query.
> > > 
> > > Say I have a query that returns 5 strings on average of 20 chars each.
> > > 
> > > The query returns 5000 rows.
> > > 
> > > I know this seems high but just humor me and remember I have access 
> > > to big servers here at Sun :)
> > > 
> > > Nathan
> > > 
> > 
> > 
>

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