#! perl -sw
use strict;
use threads;
use Thread::Queue;
use Time::HiRes qw[ time ];

sub worker {
    my $Q = shift;
    while( my $line = $Q->dequeue ) {
         $line =~ s[a][A]g;
         print $line;
    }
}

print "Started " . scalar locatime;
our $T //= 4;
my $n = $T -1;

my @Qs = map Thread::Queue->new, 0 .. $n;

my @threads = map{
    threads->create( \&worker, $Qs[ $_ ] )
} 0 .. $n;

my $start = time;
my $i = 0;
while( <> ) {
    $Qs[ $i ]->enqueue( $_ );
    $i = ( $i + 1 ) % $T;
    warn $., ' ', $. / ( time - $start ) unless $. % 1e6;
}

$Qs[ $_ ]->enqueue( undef ) for 0 .. $n;

$_->join for @threads;

print "Ended " . scalar locatime;

##</code><code>##

perl -e"printf qq[line %6d:the quick brown fox jumps over the lazy dog\n], $_ for 1 .. 1e6" >phrases.small

C:\test>dir phrases.small
...
23/03/2011  03:19        57,000,000 phrases.small
...

##</code><code>##

C:\test>junk71 -T=1 phrases.small >out.txt
Started Wed Mar 23 03:19:58 2011
1000000 19484.8213140505 at C:\test\junk71.pl line 30, <> line 1000000.
Ended Wed Mar 23 03:20:51 2011

C:\test>junk71 -T=2 phrases.small >out.txt
Started Wed Mar 23 03:20:59 2011
1000000 18001.4760827208 at C:\test\junk71.pl line 30, <> line 1000000.
Ended Wed Mar 23 03:21:55 2011

C:\test>junk71 -T=3 phrases.small >out.txt
Started Wed Mar 23 03:27:32 2011
1000000 15906.3434420465 at C:\test\junk71.pl line 30, <> line 1000000.
Ended Wed Mar 23 03:28:35 2011

C:\test>junk71 -T=4 phrases.small >out.txt
Started Wed Mar 23 03:30:32 2011
1000000 15088.645826608 at C:\test\junk71.pl line 30, <> line 1000000.
Ended Wed Mar 23 03:31:38 2011

##</code><code>##

perl -MTime::HiRes=time 
-E"BEGIN{warn $t=time, }" 
-pe"s[a][A]g; }{ warn $./(time-$t); warn time" 
phrases.small >out.txt

1300851145.745 at -e line 1.
977517.104726817 at -e line 2, <> line 1000000.
1300851146.77491 at -e line 2, <> line 1000000.