Re: Object creation overhead

From: nos (nos_at_nospam.com)
Date: 11/27/03 

Date: Thu, 27 Nov 2003 00:10:00 GMT

please, what is a "proxy" object? how to make one?

"Anthony Borla" <ajborla@bigpond.com> wrote in message
news:jUaxb.28464$aT.27175@news-server.bigpond.net.au...
>
> "Richard" <richard@praxistech.com> wrote in message
> news:PW5xb.174421$jy.168107@clgrps13...
> >
> > Hi all,
> >
> > I am looking for some help on understanding the overhead
> > associated with object creation in Java.
> >
> > I am writing an application where I have written a class to
> > encapsulate some text data.
> >
> > The class is contains these private variables:
> >
> > // private variables
> > private String id = null;
> > private String subject = null;
> > private String from = null;
> > private String date = null;
> > private String bytes = null;
> > private String lines = null ;
> > private boolean isread;
> > private String server = null;
> > private int port;
> > private String group = null;
> >
> >
> > Now I create each object with no parameters passed into
> > the constructor, and manually populate 6 of the String variables
> > indicated above. Also the server, port and group variables are
> > populated for each object instance.
> >
> > Of course there are accessor methods to deal with accessing
> > the private variables, in total about 29 methods for this class.
> > The Class implements Serializable and Comparable.
> >
> <SNIP>
> >
> > Any suggestions on how to reduce the memory footprint of
> > this class?
> >
>
> General approaches:
>
> * Reduce the size of each object
>
> - Use 'proxy' objects to represent each 'real' object.
> When the proxy is selected, the 'real' object is
> instantiated from data stored elsewhere [e.g. in
> a database, file, or cache]
>
> - Minimise the number of fields in each object. For
> example, instead of using separate 'String' objects
> to store data such as 'subject', 'from', etc, just use a
> single 'StringBuffer' to hold *all* this data, and
> extract it from the 'StringBuffer' via accessors.
> The 'StringBufferReader/Writer' classes could help
> here
>
> - Use alternate means to represent object data. For
> example, instead of pbjects like 'String', encode data
> in 'int' primitives and decode using bitwise operations
> via accessors
>
> * Reduce the number of objects in memory at the same
> time, something that will, of course, require a redesign.
> Not knowing your requirements prevents a detailed
> response, but here are a few ideas:
>
> - Adopt a database approach i.e. objects stored
> externally and only retrieved on demand [probably
> not feasable for you, but I thought I'd mention it :)]
>
> - Use a some sort of caching system e.g. keep only
> frequently accessed items in memory, etc
>
> - If needing to process the whole chunk of objects
> alter your algorithms to work on subsets ata a time
>
> In general, I'd question the need to keep that many objects in memory [but
> of course I don't know your requirements]. Hopefully, though, you now have
a
> few ideas to consider.
>
> >
> > p.s. in a similar app written in c++, the same List consumes
> > about 18MB, and I am trying to get a similar memory footprint
> > as this....
> >
>
> Not surprising since there is no JVM and library routines to load into
> memory :) !
>
> I hope this helps.
>
> Anthony Borla
>
>

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