MYLOOP: while ( 1 ) {

   open my $fh1, '<', "$file1" or do {
      print STDERR "unable to open $file1: $!\n";
      print STDERR "sleep for 3 seconds\n";
      sleep 3;
      print STDERR "wakeup\n";
      next MYLOOP;
   };

   # irgendeine Verarbeitung
   close $fh1;

   open my $fh2, '<', "$file2" or do {
      print STDERR "unable to open $file2: $!\n";
      print STDERR "sleep for 3 seconds\n";
      sleep 3;
      print STDERR "wakeup\n";
      next MYLOOP;
   };

   # irgendeine Verarbeitung
   close $fh2;

   open my $fh3, '<', "$file3" or do {
      print STDERR "unable to open $file3: $!\n";
      print STDERR "sleep for 3 seconds\n";
      sleep 3;
      print STDERR "wakeup\n";
      next MYLOOP;
   };

   # irgendeine Verarbeitung
   close $fh3;

}