#! perl -slw
use strict;
use threads;
use threads::shared;
use Thread::Queue;
use LWP::Simple;
use Time::HiRes qw[ time ];

$|=1;
our $THREADS	||= 3;
our $DELAY		||= 10;

sub ping {
	my( $Q, $done ) = @_;
	my $tid = threads->self->tid;
	while( not $$done ) {
		my( $time, $url ) = split ':', $Q->dequeue;
		select undef, undef, undef, 0.01, while time < $time;
		my $start = time;
		printf "($tid) %20s returned [%50.50s] and took %f seconds\n"
			, $url
			, join( ' ', grep{ defined } head( "http://$url" ) )
			, time() - $start
		;
		$Q->enqueue( ( $DELAY + time() ) . ":$url" );
	}
}

my $Q = new Thread::Queue;
$Q->enqueue( map{ chomp; time() . ":$_" } <DATA> );

my $done : shared = 0;
my @threads = map{ threads->new( \&ping, $Q, \$done ) } 1 .. $THREADS;

<STDIN>;
print "Stopping...";

$done = 1;
$_->join for @threads;

__DATA__
www.yahoo.com
www.aol.com
www.altavista.com
www.time.com
www.whitehouse.gov
www.parliament.uk
www.scottish.parliament.uk
www.europarl.org.uk
www.nasa.com
www.perl.com
www.perl.org
www.activestate.com
www.bbc.co.uk
www.ibm.com
www.google.com
www.cnn.com
www.perlmonks.com
www.microsoft.com