多线程-php单例问题 疑问求解答

多线程phpsingleton

A.php

<code><?php class Singleton  {      private static $instance;          private function __construct()      {          echo "This is ok!\r\n";    }      public static function GetInstance()      {          if (!(self::$instance instanceof self))          {              self::$instance = new self();          }          return self::$instance;      }  }  </code></code>

B.php

<code><?phprequire_once ('A.php');class AsyncOperation extends Thread {  public function __construct($arg){    $this->arg = $arg;  }  public function run(){    if($this->arg){      Singleton::GetInstance();    }  }}$arr = array();for($i=0;$istart();}</code>

本人写java的 看到php的单例如A.php表示，但是实际在pthreads扩展下多线程跑的时候，会打印出内容，多次构造该实例。求各位phper解答疑问

对java熟悉点，java中

<code>public class Singleton{    private static Object instance = null;    public Object getInstance(){        if(instance==null){            synchronized(Singleton.class){                if(instance==null){                    instance = new Singleton();                }            }        }        return instance    }}</code>