How can i delete perl stuff from memory. I've understood that commands like delete, shift and undef do these. But it doesn't seem to be so. Test code below (uses ~170M memory). I watched memory usage with gtop. What happens to memory after is has been removed from perl (shift/undef/delete etc)? Can it be reused by other apps? Perl itself might be able to reuse, but i haven't tested enough to make more certain points.

#!/usr/bin/perl
#
# Testing memory usage...
use warnings;
use strict;

my (%hash,@array);
my ($i,$j)=(0,0);
$|=1;
while ($i<2000) {
  while ($j<1000) {
    push (@{$array[$i]},$j);
    push (@{$hash{$i+1}},$j);
    $j++;
  }
  $i++;
  $j=0;
  print "\r$i";
}

print "\nLoaded. Sleeping little.\n";
sleep 15;
print "Copying for undef.\n";
my %new_hash=%hash;

print "Deleting hash.\n";
$i=0;
foreach (sort {$a<=>$b} keys %hash) {
  delete $hash{$_};
  $i++;
  print "\r$i";
}

print "\nDone, sleeping\n";
sleep 10;
print "Shifting array.\n";
$i=0;
foreach (@array) {
  shift @array;
  $i++;
  print "\r$i";
}

print "\nDone. Sleeping.\n";
sleep 10;

print "Undefing new_hash.\n";
undef %new_hash;
print "Sleeping.\n";
sleep 10;
print "Exit.\n";
exit 0;
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