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From Chase Venters <>
Subject Re: Questions about optimizing memory usage
Date Fri, 16 Dec 2005 17:52:45 GMT
On Fri, 16 Dec 2005, Perrin Harkins wrote:

> It will probably be big.  Perl structures tend to use several times the
> size of the actual data they store.

That's what I'm worried about then I suppose.

>> is this root hash, its keys / values / etc stored along with variables, or is
>> it in the op tree?
> I assume that it's stored in exactly the same way all the other
> variables are stored.

I wonder then if Perl would be smart enough to understand that the data is 
constant and not copy it with Perl_clone()? I suppose what I really should 
be doing here is writing a test as a perl embedded app that does various 
things to test out clone's behavior.

>> I can't put the data in SQL for performance reasons.
> Have you tried?  It's hard for me to believe that the data can't be
> broken down in a way that would make external storage possible.

Actually tried? No. But the data is in essence a big table of information 
about how to build SQL queries from method calls, validate/convert the 
information in the process, and pack it into objects. Having to first 
fetch the model itself out of SQL (its structure not even lending to easy 
storage in such a DB) would be clunky / awkward, and would basically 
involve an extra query or set of queries against a table for every 

Now, admittedly, I'm an extreme freak when it comes to optimizing for 
performance. In the age of J2EE, it's how I make my stuff shine. Seeing 
low-ms response times from mod_perl apps makes me smile.

>> And BDB would be dependency creep, which
>> is quite difficult to fight in perl sometimes (that's just because there are
>> a zillion useful CPAN modules) :)
> Personally, I don't fight it.  I just use zillions of CPAN modules.

Genearlly so do I. And so do the authors of those modules. Then one day 
you're installing Net::SSH::Perl and you realize that it pulls in fifteen 
module distribution dependencies once everything is accounted for.

I now understand the meaning of autosplit :)

> - Perrin

Thanks again for your remarks.


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