how to improve Performance for this code? - performance

Question

this code is running on a file of 200M lines at least. and this takes a lot of time
I would like to know if I can improve the runtime of this loop.
my #bin_lsit; #list of 0's and 1's
while (my $line = $input_io->getline) {
if ($bin_list[$i]) {
$line =~ s/^.{3}/XXX/;
} else {
$line =~ s/^.{3}/YYY/;
}
$output_io->appendln($line);
$i++;
}

Answer 1

A regex solution may be overkill here. How about replacing the if/else blocks with:
substr($line, 0, 3, $bin_list[$i] ? 'XXX' : 'YYY';

Answer 2

Smallest change is probably to buffer between appendln's
my #bin_lsit; #list of 0's and 1's
my $i = 0;
while (my $line = $input_io->getline) {
if ($bin_list[$i]) {
$line =~ s/^.{3}/XXX/;
} else {
$line =~ s/^.{3}/YYY/;
}
$buffer .= $line;
if ( $i % 1000 == 0 ) {
$output_io->appendln($buffer);
$buffer = '';
}
$i++;
}
if ( $buffer ne '' ) {
$output_io->appendln($buffer);
}
Are you using IO::All?
I couldn't find anything else with appendln...
Replacing this:
my $input_io = io 'tmp.this';
my $output_io = io 'tmp.out';
while (my $line = $input_io->getline ) {
$output_io->appendln($line);
}
With this:
open(IFH, 'tmp.this');
open(OFH, '>>tmp.out');
while (my $line = <IFH> ) {
print OFH $line;
}
close IFH;
close OFH;
Is quite a bit faster (1 sec vs 23 in my test case).