my $COMMIT_CHUNK_SIZE;
my $line_num;
my $row = [ ... ];

##</code><code>##

my $cnt_COMMIT_CHUNK_SIZE;
my $cnt_line_num;
my $db_row = [ ... ];

##</code><code>##

if ($db_row and ($db_row % $cnt_COMMIT_CHUNK_SIZE == 0)) {
    $dbh->commit;
}