php多线程有用吗

<?php
 class test_thread_run extends Thread 
 {
 public $url;
 public $data;
 
 public function __construct($url)
 {
 $this->url = $url;
 }
 
 public function run()
 {
 if(($url = $this->url))
 {
 $this->data = model_http_curl_get($url);
 }
 }
 }
 
 function model_thread_result_get($urls_array) 
 {
 foreach ($urls_array as $key => $value) 
 {
 $thread_array[$key] = new test_thread_run($value["url"]);
 $thread_array[$key]->start();
 }
 
 foreach ($thread_array as $thread_array_key => $thread_array_value) 
 {
 while($thread_array[$thread_array_key]->isRunning())
 {
 usleep(10);
 }
 if($thread_array[$thread_array_key]->join())
 {
 $variable_data[$thread_array_key] = $thread_array[$thread_array_key]->data;
 }
 }
 return $variable_data;
 }
 
 function model_http_curl_get($url,$userAgent="") 
 {
 $userAgent = $userAgent ? $userAgent : 'Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.2)'; 
 $curl = curl_init();
 curl_setopt($curl, CURLOPT_URL, $url);
 curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
 curl_setopt($curl, CURLOPT_TIMEOUT, 5);
 curl_setopt($curl, CURLOPT_USERAGENT, $userAgent);
 $result = curl_exec($curl);
 curl_close($curl);
 return $result;
 }
 
 for ($i=0; $i < 100; $i++) 
 { 
 $urls_array[] = array("name" => "baidu", "url" => "http://www.baidu.com/s?wd= ".mt_rand(10000,20000));
 }
 
 $t = microtime(true);
 $result = model_thread_result_get($urls_array);
 $e = microtime(true);
 echo "多线程：".($e-$t)."\n";
 
 $t = microtime(true);
 foreach ($urls_array as $key => $value) 
 {
 $result_new[$key] = model_http_curl_get($value["url"]);
 }
 $e = microtime(true);
 echo "For循环：".($e-$t)."\n";
 ?>