Writing a simple HTTP spider using POE

Hello, I am new to POE and event/driven programming, I hope you guy
can give some adivce for me.

Now, I am writing a simple HTTP spider, which based the code from:
http://poe.perl.org/?POE_Cookbook/Web_Client


#=================================
use HTTP::Request::Common qw(GET POST);
use POE qw(Component::Client::HTTP);

my @url_list = ( XXX );

POE::Component::Client::HTTP->spawn( Alias => 'ua' );

sub got_response {
    my ( $heap, $request_packet, $response_packet ) = @_[ HEAP, ARG0, ARG1 ];

    my $http_request  = $request_packet->[0];
    my $http_response = $response_packet->[0];

    my $response_string = $http_response->as_string();
    $response_string =~ s/^/| /mg;
    print ",", '-' x 78, "\n";
    print $response_string;
    print "`", '-' x 78, "\n";
}

sub _start {
    my $kernel = $_[KERNEL];

    foreach my $url (@url_list) {
        $kernel->post( "ua" => "request", "got_response", GET $url);
    }
}

POE::Session->create(
    package_states => [ main => [ "_start", "got_response" ] ]
);

$poe_kernel->run();

#=================================

My quesionts are:

1. Suppose using the above code, my computer will download pages as
fast as possible using single thread?
2. Is it possible to enhance if I am using multi-core CPU?
3. If I insert a 3rd party module call within "got_response", such as
logging using Log-Log4perl, is it always thread safe?


Thanks for any suggestions.

Howard