You could set it up so that each shuffle is done after a fork, and just wait for that one to end/die before going to the next. Something like (untested; off top of head & docs, but i think is the general outline):

my @deck = create_deck();
while(1){  # or whatever; loop over specific deals, or do just N deals
+, etc.
  my $pid = fork;
  die unless defined $pid;
  if($pid){  # parent
    wait;
    # report on $? if desired
    next;
  }
  do_heavy_lifting(\@deck);
  exit;  # w/an error code based on result if desired
}

sub do_heavy_lifting {
  ...
  my %positions = ....;
  ...
}
[download]

So the %positions isn't created/populated (made huge) until in the fork'd process, so when that exits, the memory will get freed to the system, but your program is still going from the parent process.

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