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.

In reply to Re^3: why won't the hash go away? by davidrw
in thread why won't the hash go away? by WoodyWeaver

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