I have a program that plays solitaire.

There is a humungous data structure %positions. It looks something like this: 


do {
  require MIME::Base64;
  (
    MIME::Base64::decode("2qyANnIPJvTGkGfTQ8PTHtBUaKY4qm6eP8eTiC2MFzej
+iJLwnIwZayMREOmyRFgJ+3IHdV1fja3Y4lq3smfArLVhRVYYzbV1ZOVTw9aelSthia4Bq
+2pAw5Ws/StQvBNao1fpirK8Zq9Q4iDDuQY="),
    {
      desc   => "move 4C from col 4 to 0 turning a card (88)",
      metric => 5295,
      parent => MIME::Base64::decode("2qyANnIPJvTGkGfTQ8PTHtBUaKY4qm6e
+P8eTiC2MFzejiJLwnIwZayMREOmytBL25Q7qur4aW7HFtW5lz4BZa8OKrDCaa2vCyqeGR
+daelSthia4Bq2pAw5Ws/StQvBNao1fpirK8Zq9Q4iDDuQY="),
    },
    MIME::Base64::decode("2qyANnIPJvTGkGfTQ8PTHtBUaKY4qm6eP8eTiC2MFzej
+iJLwnIwZayMREOmytBL25Q7qur4aW7HFtW5lz4BZa4NnRVYYzbU1YeVTwyLr6MqVsKwBq
+2pAw5Ws/StQvBNao1fpirK8Zq9Q4iDDuQY="),
    {
      desc   => "move 9H from col 5 to 3 turning a card (92)",
      metric => 5291,
      parent => MIME::Base64::decode("2qyANnIPJvTGkGfTQ8PTHtBUaKY4qm6e
+P8eTiC2MFzejiJLwnIwZayMREOmytBL25Q7qur4aW7HFtW5lz4BZa8OKrDCaa2vCyqeGR
+daelSthia4Bq2pAw5Ws/StQvBNao1fpirK8Zq9Q4iDDuQY="),
    },
...
    MIME::Base64::decode("2qyANnIPJvTGkGfTQ8PTHtBUaKY4qm6eP8eTiC2MFzej
+iJLLknQl7Msd1HUdshpbscW1DrGyZ8CstQG5IiuM5tqa0F751LDI2hNbuRKW6BrAXFUDG
+q5k7ZetQPFOaI3OrdIVZXnNhq9Q4iDDuQY="),
    {
      desc   => "deal cards (-208)",
      metric => 5591,
      parent => MIME::Base64::decode("2qyANnIPJvTGkGfTQ8PTHtBUaKY4qm6e
+P8eTiC2MFzejiJLwnIwZayMREOmytBL25Q7qur4aW7HFtW5lz4BZa8OKrDCaa2vCyqeGR
+daelSthia4Bq2pAw5Ws/StQvBNao1fpirK8Zq9Q4iDDuQY="),
    },
    MIME::Base64::decode("2qyANnIPJvTGkGfTQ8PTHtBUaKY4qm6eP8eTiC2MFzej
+iJLwnIwZayMREOmytBL25Q7qur4aW7HFtW5lz4BZa8OKrDCaa2vCyqeGRdaelSthia4Bq
+2pAw5Ws/StQvBNao1fpirK8Zq9Q4iDDuQY="),
    { desc => "initial deal", metric => 5383 },
  );
}

[download]
After a couple of hours, the memory used by the perl app is several gigs in size, and I assume its due to this guy. Anyway, after running for several hours, my program gets tired of playing that hand and wants to play another. It goes to a re-initialization script that has a segment like this: 
  $|=1;
  open F, ">>state.txt";
  my $position = Spider::unmash($best);
  movestack($position, $best, ">lastpos".$$.".txt", 1);
  print F scalar localtime(time), "Moved stack\n";
  close F;
  open F, ">>state2.txt";

  %positions = ();
  print F scalar localtime(time), "Reset positions\n";
  close F;

[download]
The file state.txt gets updated appropriately, while state2.txt doesn't -- it just hangs. On the other hand, when %positions isn't that humungous -- say if I sigint after only ten minutes, or it finds a solution -- then the hash gets cleared and all is well.

I thought about breaking the hash into 32nds or something, and doing a pre-hash before looking up the hash key, to keep %positions fairly small, but that seems like such a crock. (And frankly, I don't care that much. If while playing solitaire my computer zones out, well, no harm done.)

Is there a better way than %positions = () to clear a hash?

--woody

In reply to why won't the hash go away? by WoodyWeaver

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