这两个函数的唯一区别是,pfsockopen是持续连接,而fsockopen不是.
我写了个代码了一下:

$data="1,0,721,73,1,0,0,43290000,0,60D81D509BC00451,3,FFFFFFFF";
//http://10.144.99.114/SANEX_NEW/modules/subscribemanager/test.php
$host = '127.0.0.1';
$url = "/aa.php";
$pffirst = false;
$times = 1000;
$startTime = microtime(true);
for ($index = 0; $index < $times; $index++) {
 echo httpPost($host,$url,$data,$pffirst)."

---

";
}
$middleTime = microtime(true);
for ($index = 0; $index < $times; $index++) {
 echo httpPost($host,$url,$data,!$pffirst)."

---

";;
}
$endTime = microtime(true);
 echo ($pffirst?"pfsocket":"fsocket").":".($middleTime-$startTime);
 echo "
";
 echo ($pffirst?"fsocket":"pfsocket").":".($endTime-$middleTime);

$count=0;
//发包函数
function httpPost($host,$url,$data,$p)
{
global $count;
 $func = $p?"pfsockopen":"fsockopen";

 $conn = $func($host,80,$errno, $errstr, 30);
 if (!$conn)
 {
  echo "$errstr ($errno)
\n";
  return;
 }

 $header = "POST ".$url." HTTP/1.1\r\n";
 $header.= "Host : {$host}\r\n";
 $header.= "Content-type: application/x-www-form-urlencoded\r\n";
 $header.= "Content-Length:".strlen($data)."\r\n";
 $header.= "Connection: Keep-Alive\r\n\r\n"; 
 $header.= "{$data}\r\n\r\n";

 fwrite($conn,$header);

 $count++;
 echo $count.' '.$header."

";

 $resp='';
 //while (!feof($conn)) {
 // $resp .= fgets($conn);
 //}
 //fclose($conn);
 return $resp;
}
?>

结果发现:
代码的倒数第二行,如果把//fclose($conn);注释掉,结果是:
fsocket:11.04693198204
pfsocket:0.34867787361145

如果不注释:
fsocket:12.509312152863
pfsocket:11.120275974274
可以看出,fsocketopen默认每次处理结束后,就算协议头是Keep-Alive,连接仍然断掉了.
而pfsocketopen在Keep-Alive条件下,连接可以被下一次重复利用.
一次连接发送大量数据时,推荐使用pfsocketopen