As I understand it altering variables from within sig-handlers can sometimes go wrong since perl's code isn't reenterent. Another way of accomplishing your goal to avoid this possible problem would be to give each child a portion of the list.
Something like this:

my @list = (1..2000);
my $kids = 20;
my $num_per_kid = int (@list / 20);

for my $chld (1..$kids) {
 my @tmp = @list[(($chld-1)*$num_per_kid)..($chld==$kids ? $#list : $c
+hld*$num_per_kid)];
 if (fork) {
  for my $item (@tmp)
  {
   print "$_\n";
  }
 }
}
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