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Re: Re: A memory efficient hash, trading off speed - does it already exist?

by JPaul (Hermit)
on Feb 04, 2003 at 04:21 UTC ( [id://232459]=note: print w/replies, xml ) Need Help??


in reply to Re: A memory efficient hash, trading off speed - does it already exist?
in thread A memory efficient hash, trading off speed - does it already exist?

I tried this earlier on when it became apparent the project would be sucking up great quantities of memory - with very little success. In fact, I think it changed the memory usage by less than a few hundred kilobytes...
This was some time ago, the data set has changed greatly. Perhaps I should try this again and would benefit more from it with a more diverse data set.

I don't even begin to understand that second paragraph. It amazes me how much I can do in perl, and how remarkably little I truly understand about the workings of it all. How embaressing.

My thanks,
JP
-- Alexander Widdlemouse undid his bellybutton and his bum dropped off --

  • Comment on Re: Re: A memory efficient hash, trading off speed - does it already exist?

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An interesting OO representation (was Re3: A memory efficient hash, trading off speed - does it already exist?)
by dragonchild (Archbishop) on Feb 04, 2003 at 15:14 UTC
    Let's say you know you will be making a hash of 120,000 hashes, each with (up to) 2 values. Instead of making 120,000 tiny hashes, with the overhead of each hash, you can go ahead and make 120,000 blessed scalar-refs and one huge array of 360,000 scalars. Each object will be a blessed scalar. Something like (untested!):
    package CoolObject; my @objects; my $next_index = 0; sub new { my $class = shift; my $x = $next_index; my $self = bless \$x, $class; $next_index += 3; return $self; } sub name { my $self = shift; $object[$$self] = shift if @_; return $object[$$self]; } sub attr1 { my $self = shift; $object[$$self + 1] = shift if @_; return $object[$$self + 1]; } sub attr2 { my $self = shift; $object[$$self + 2] = shift if @_; return $object[$$self + 2]; } 1;
    Those having read the Panther book will recognize this. Some obvious improvements would include:
    1. Adding the kind of garbage collection he had to re-use entries. (This would be in DESTROY.)
    2. Initialization of attributes. (This would be in new)
    3. Making it into more of a base class that will take attributes. (This would involve adding some sort of attribute registration.)
    4. Adding attribute inheritance. (This would involve attribute registration that walks the ISA-tree.)

    ------
    We are the carpenters and bricklayers of the Information Age.

    Don't go borrowing trouble. For programmers, this means Worry only about what you need to implement.

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