use Data::Dumper;
use MLDBM qw( DB_File );
use Fcntl qw( :DEFAULT :flock );

sub hash_init2  {
    #### DBM Configuration #######################
    my $dbm_file = "file.db";
    my %hash;
    local *DBM;

    my $db = tie %hash, 'MLDBM', $dbm_file, O_CREAT | O_RDWR, 0644
        or die "Couldn't not tie to $dbm_file: $!";
    my $fd = $db->fd;
    open DBM, "+<&=$fd" or die "Could not dup DBM for lock : $!";
    flock DBM, LOCK_EX;
    undef $db;

    return \%hash;
}

my $h = hash_init2();
print Dumper $h;