MYLOOP: while ( 1 ) {

  open my $fh1, '<', "$file1" or foobar($file1) and next;
  # irgendeine Verarbeitung
  close $fh1;

  open my $fh2, '<', "$file2" or foobar($file2) and next;
  # irgendeine Verarbeitung
  close $fh2;

  open my $fh3, '<', "$file3" or foobar($file3) and next;
  # irgendeine Verarbeitung
  close $fh3;

}

sub foobar {
  my $file = shift;
  print STDERR "unable to open $file: $!\n";
  print STDERR "sleep for 3 seconds\n";
  sleep 3;
  print STDERR "wakeup\n";
}