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in reply to why won't the hash go away?

You may want to consider mapping your game states to persistant storage using DBM::Deep(or similar).

Not only do you free up memory; you get free game persistance. Saving and switching between games becomes near instantaneous.

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Re^2: why won't the hash go away?
by WoodyWeaver (Monk) on Jan 13, 2008 at 00:17 UTC
    ...but oh, the cost! This is a search algorithm, and the "trick" is to avoid having to search a node twice; the underlying game is "Spider", and there is a lot of repetitions between positions. So the hash lookup gets done *a lot*. By making it a tie, now not only do I have to do something fancy to invoke the tie, but I'm going to be bogged down my disk access.

    Of course, the thrashing means I'm bogged down by disk access as well, so...

[reply]
      >> but I'm going to be bogged down my disk access:

      Hmm, I'd be interested to see how DBM::Deep plays with open's mmap option (as of yet untested/unbenchmarked): 

      open(DATA, '<+:mmap', 'game.dbm')
my $db = DBM::Deep->new( { fh => \*DATA } );

      [download]
      Update: Have benchmarked. No appreciable benefits with the above :-|

      Now looking at the storage => ... option.

[reply]
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