sub Pooled_function {

  open(my $STDOUT_SAVE, ">&STDOUT"); # save current STDOUT

  while (<$parentfh>) {
    chomp;
    my ($pclass, $copy_to_console) = split(' ', $_, 2);
    my $file = ...;
    if ($copy_to_console) {
      open(STDOUT, ">&", $STDOUT_SAVE);
      open(OUT, "|-", "tee", $file);
    } else {
      open(OUT, ">", $file);
    }
    open(STDOUT, ">&OUT");
    open(STDERR, ">&OUT");

    # Do the stuff

    close(STDOUT);
    close(STDERR);
    close(OUT);
  }
  close($parentfh);
}