02/02/2015  15:42    10,737,418,241 big.csv
02/02/2015  15:47    12,300,000,001 big.tsv

##</code><code>##

#! perl -slw
use strict;
use threads;
use Time::HiRes qw[ sleep time ];

sub worker {
    my( $file, $start ) = @_;
    open my $in, '<', $file or die $!;
    sleep 0.0001 while time() < $start;
    my $count = 0;
    ++$count while <$in>;
    my $stop = time;
    return sprintf "$file:[%u] %.9f", $count, $stop - $start;
}

my $start = time + 1;
my @workers = map threads->create( \&worker, $_, $start ), @ARGV;

print $_->join for @workers;

for my $file (@ARGV) {
    open my $in, '<', $file or die $!;
    my( $start, $count ) = ( time(), 0 );
    ++$count while <$in>;
    printf "$file:[%u] %.9f\n", $count, time()-$start;
}

__END__
[15:49:22.32] E:\test>c:piotest.pl big.csv big.tsv
big.csv:[167772161] 407.047676086
big.tsv:[100000001] 417.717574120
big.csv:[167772161] 82.103285074
big.tsv:[100000001] 81.984734058