#! perl -sw
use strict;
use threads;
use threads::shared;
use Thread::Queue;

sub worker {
    my( $Qin, $outRef ) = @_;
    while( my $in = $Qin->dequeue ) {
        my( $no, $text ) = split ':', $in, 2;
        ########## Manipulate data below ########
        my $out = $text;
        lock $outRef;
        $outRef->[ $no ] = $out;
    }
}

my @out :shared;
my $Qin = new Thread::Queue;

my @threads = map threads->create( \&worker, $Qin, \@out ), 1 .. 4;

my $last :shared = 0;

async {
    while( <> ) {
        sleep 1 while $Qin->pending > 100;
        $Qin->enqueue( "$.:$_" );
        lock $last;
        $last = $.;
    }
};

my $next = 1;

while( threads->list( threads->running ) ) {
    sleep 1 until defined $out[ $next ];
    print $out[ $next ];
    undef $out[ $next++ ];
}

while( $next < $last ) {
    sleep 1 until defined $out[ $next ];
    print $out[ $next ];
    undef $out[ $next++ ];
}

$_->join for @threads;