#! perl -slw
use strict;
use LWP::Simple;
use threads stack_size => 4096;
use threads::shared;
use Thread::Queue;

our $THREADS //= 500;

my %log :shared;
my $Q = new Thread::Queue;

my @threads = map async( sub {
    while( my $url = $Q->dequeue() ) {
        my @info = head 'http://' . $url;
        lock %log;
        $log{ $url } = join $;, map{ local $^W; $_ // '*n/a*' } @info;
    }
} ), 1 .. $THREADS;

while( <> ) {
    chomp;
    sleep 1 if $Q->pending > $THREADS;
    $Q->enqueue( $_ );
}

$Q->enqueue( (undef) x $THREADS );

$_->join for @threads;

my( $url, $status );
print "$url : $status" while ( $url, $status ) = each %log;

__END__
c:\test>t-head-urls -THREADS=100 urls.list.small
www.t-mobile.com : text/html; charset=utf-8?109511?873075813?*n/a*?Microsoft-IIS/7.0
www.avocent.com : text/html; charset=UTF-8?114030?*n/a*?*n/a*?Microsoft-IIS/7.0
www.fsw.com : text/html?9926?1306121940?*n/a*?Apache/2.2.21 (Unix) mod_ssl/2.2.21 OpenSSL/0.9.7a mod_auth_passthrough/2.1 mod_bwlimited/1.4 FrontPage/5.0.2.2635 mod_fcgid/2.3.5 Resin/3.1.10 Sun-ONE-ASP/4.0.3
www.voodoopc.com : text/html?6021?*n/a*?1328712575?Apache
www.creative.com : text/html; Charset=iso-8859-1?42330?*n/a*?1328705318?Microsoft-IIS/6.0
www.belkin.com :
www.argus-systems.com : text/html?8111?1320697393?*n/a*?Apache/2.2.6 (Unix) mod_python/3.3.1 Python/2.5.1 mod_ssl/2.2.6 OpenSSL/0.9.8g
www.iss.net : text/html; charset=UTF-8?*n/a*?*n/a*?*n/a*?Apache
www.Joyent.COM : text/html; charset=UTF-8?*n/a*?*n/a*?*n/a*?Apache
...