perl script with AnyEvent is not going fast enough - perl

Question

Here is the little script I created to do HTTP transactions from a file with a list of URLs. The problem is that it's not able to do HTTP transactions as fast as I would like. More precisely, I set the rate to be 200/seconds, but it was able to send only at about 50/second. The server is powerful enough to handle 100/second.
This was run on a powerful PC with E5-1650 CPU and 64GB of RAM running Ubuntu 14.04 desktop. When the script runs, the CPU usage is only about 12%. The command I used was perl httpStresser.pl urlList rate 200.
Any idea why?
use AnyEvent;
use EV;
use AnyEvent::HTTP;
use AnyEvent::Handle;
use Time::HiRes qw( gettimeofday );
my $expectedRespCode = 200;
my $rate = 1;
my #urls = ();
readUrls(shift);
my $numOfUrls = $#urls;
my $start = time();
my $printed = 0; #have we printed the completion msg.
my $gId = 0;
my $spawned;
my #ctx = ();
my $i;
for ($i=0; $i<=$#ARGV; $i++) {
if ($ARGV[$i] =~ /^expect/) {
$expectedRespCode = $ARGV[$i+1];
$i++;
} elsif ($ARGV[$i] =~ /^rate/) {
$rate = $ARGV[$i+1];
print "rate is now $rate\n";
$i++;
} elsif ($ARGV[$i] =~ /^skip/) {
$gId = $ARGV[$i+1];
$i++;
} else {
die "only max, stayup are supported\n";
}
}
my $spawned = 0;
my $w = AnyEvent->condvar;
$| = 1;
my $start = getTS();
my $_timer;
$_timer = AnyEvent->timer(after => 0, interval => 0.001, cb => ::timeoutHandler);
$w->recv;
sub kickoff {
my $id = $gId ++;
if ($id > $numOfUrls) {
if ($printed == 0) {
print "done!!\n"; $printed = 1;
}
return;
}
#print "$id\n";
http_get $urls[$id], headers => { }, sub {
my $statusCode = $_[1]->{Status};
#printf "status $statusCode %d\n", time() - $start;
if (($id % 100) == 0) {
print "$id\n";
}
if ($statusCode != $expectedRespCode) {
print "unexpected resp code $id:$statusCode $urls[$id]\n";
}
};
}
sub timeoutHandler {
#print time(), "|\n";
if (! defined $start) {
$start = getTS(); kickoff(); $spawned = 1; return;
}
my $delta = getTS() - $start;
my $target = $delta * $rate;
#printf "%.4f %4d $spawned\n", $delta, $target;
for (; $spawned <= $target; $spawned++) {
kickoff();
}
if ($delta >= 1.0 ) {
$start += 1.0; $spawned = 0;
}
}
sub readUrls {
my $fname = shift;
my $line;
open FD, $fname || die "Failed to open $fname $!\n";
while (<FD>) {
chomp($line = $_);
push #urls, $line;
}
close FD;
}
sub getTS {
my ($seconds, $microseconds) = gettimeofday;
return $seconds + (0.0+ $microseconds)/1000000.0;
}